RESEARCH

WORK

ARGILLACEOUS

ON

CLAY

ROCKS

MINERALS

AND

IN CZECHOSLOVAKIA

by JIi~i KONTA Institute of Petrology, Charles University, Prague ABSTRACT The investigation of clay minerals a n d argillaceous rocks started in the territory of Czechoslovakia as early as the later p a r t of the eighteenth century a n d has continued up to today. During this long period m a n y interesting results have been obtained. I n a b o u t 1949 modern laboratory techniques were introduced. Most of the work in this country deals with the mineralogy, petrology, and geology of argillaceous rocks, the chemical composition a n d physical properties of clay materials which are useful for the purposes of the ceramic, glass, chemical, construction-engineering a n d mining industries, etc. This paper is subdivided into the following parts: (a) Classical research period; (b) Modern research period; (c) Kaolins (primary); (d) Other argillaceous rocks of sedimentary origin; (e) Bentonites; (f) Laterites a n d bauxitie rocks; (g) Clay minerals in sedim e n t a r y iron ores; (h) Clay minerals in carbonaceous rocks; (i) Clay minerals of hydrothermal origin; (j) Kinds of apparatus for DTA and gravimetrie thermal analysis; (k) Imbibometrie study using water a n d organic liquids; (1) Problems of classification and terminology.

CLASSICAL

RESEARCH

PERIOD

The large deposits of kaolin and other argillaceous rocks in Czechoslovakia have made this country well known. Various laboratories throughout the world use the kaolin from Sedlec, Bohemia, as a world kaolin standard as approved in the International Congress for Theoretical and Applied Chemistry held in Copenhagen in 1924. Clay minerals and argillaceous materials were studied in the territory of Bohemian Kingdom as early as the late eighteenth century and much work was done in the nineteenth century. For example the name "cimolite" was proposed by Klaproth (1795) for the material from Bilina, northern Bohemia, which we know today as a mixture of anauxite and amorphous SiO~. From the same locality anauxite was discovered and named by Breithaupt (1838) and more detailed work on this mineral was done by Reuss (1840). Further, a number of workers, including Zepharowich (1853), Haidinger (1861), Schrauf (1877), Kenngott (1878) and Katzer (1894) described argillaceous materials under such terms as cimolite, strakonicite, chloropal, pinguite, hocferite, bole, etc., which are not valid today. In the works of the abovenamed authors we find comprehensive megascopic descriptions of the clay 426

CLAY MINERALS AND ARGILLACEOUS ROCKS IN CZECHOSLOVAKIA 427

minerals or, to put it better, argillaceous materials, their partial chemical analyses, and finally some data on chemical and physical properties, such as solubility in acids, density, etc. During the late nineteenth-century and early twentieth-century research work in this line took definite shape, particularly from chemical and microscopical points of view. For this much credit must be paid to K o v ~ (1896; 1898a; 1898b; 1899; 1901a; 1901b; 1902-3) who strictly differentiated molecular water ( H 2 0 - ) from water of constitution (H20 + ) in the chemical analyses. Bukovsks~ (1906) also deserves some credit. Magnesium hydrosilicates from Bohemia and Moravia were studied by the well-known Russian mineralogist and geochemist Fersman (1908; 1912) and clay minerals from oSlites in sedimentary iron ores by Slavikovs and Slavik (1917). In the years to follow, up to 1949, greater emphasis was laid on quantitative chemical analysis and microscopical study; X-ray study was seldom used during this period. In the field of pedology much attention was centered around the methods of determining particle size of soil colloids. In ceramic technology the broader problems connected with plasticity, chemical purity and heat resistivity were being solved. Main workers who contributed to this work are Kallauncr and Bs (1918), Kallauner and Mat~jka (1926), Spllchal (1921-2), Sokol (1921), Kratochvil (1927), Dittler and Hibsch (1923), Noll (1930), Zartner (1932), Hibsch (1930; 1934), Bs (1930), Pcli~ek (1933), Orlov (1941a, b; 1942a, b, c; 1944), Rost (1944; 1947) and Jarka (1947). Orlov (1938a, b) also contributed many valuable chemical and petrographic data on the bauxitic rocks. The period of modern clay mineralogy and petrology research work using new laboratory methods was begun in 1949 in Czechoslovakia. This period is linked, of course, with the long-established mineralogical, petrological and chemical research traditions of the classical time. MODERN

RESEARCH

PERIOD

Publications of Czechoslovak authors in the modern period deal with an all-round study of natural clay materials for geological and industrial purposes. The characteristic feature of these works is the versatility of the methods used in the investigation of any argillaceous material or of any petrological problem: megascopic and microscopic study, X-ray analysis, differential thermal analysis, gravimetric thermal analysis, electron microscopy, chemical analysis, and often also determination of trace elements, chemical sorption, density, ion exchange, etc.

Kaolins (Primary) Most of the kaolin deposits in the Bohemian Massif were formed as products of weathering on granitic and gneissic rocks. Konta (1957) studied the kaolinites of some kaolin deposits and other clay minerals occurring in various argillaceous rocks, using chemical analysis, optical study, X-ray analysis,

428

TENr~ ~ATIONAL CONFERENCE ON CLAYS AND CLAY MINERALS

differential thermal analysis, gravimetric thermal analysis, electron microscopy and other methods. Prochs (1957) explained the relationship between the crystal structure and technological properties of kaolinites from several Czechoslovak kaolin deposits. Babfirek, Konta and Svoboda (1959) led the petrologic and geochemical investigations of the Karlsbad kaolin (deposit at Otovice) having a profile of several tens of meters. Here, besides kaolinite, they also recognized illite and a chloritic mineral. The iron released during weathering was bound by the newly formed siderite. Kulda (1959) worked on the kaolin deposits in western Bohemia and published several new chemical analyses of granite which had been kaolinized to different degrees. He also tackled the question of the age of kaolinization in this area and is of the opinion that it took place during Cretaceous and Early Tertiary time. Pouba (1959), in work based on broad geological study, came to the conclusion that kaolinization in western Bohemia took place in two different periods, namely in the Carboniferous and probably the Tertiary. The formation of ochre deposits containing illite, kaolinite and goethite, associated closely with some of these kaolin deposits, is connected with the kaolinization in this area. These are the weathered products of Proterozoic pyritic shales. Ku~vart (1960) identified various kaolinites, of structure ranging between very well and poorly developed, from some kaolin deposits in Moravia and Silesia. These kaolins were formed by weathering of gneissic and granitic rocks mainly during Early Tertiary time; some of them, however, before sedimentation of Upper Cretaceous rocks. Konta and Pouba (1961) have compiled the data available concerning the geology, mineralogy, petrography and technological properties of the western Bohemian kaolins and some ceramic clays of sedimentary origin.

Other Argillaceous Rocks of Sedimentary Origin Kallauner (1949) studied chemically and by modern methods the halloysitie rocks from Michalovce. ~atava (1949) dealt with the study of the sorption capacity of some clays having different mineralogical composition. Barta, Satava, Vachtl and Vaw (1950) studied the green clay from Von$ov. By chemical, thermal, microscopic and X-ray analysis they concluded that the predominating mineral in this clay is an illitehaving a high sorption capacity. This illite later was identified by Konta and Pouba (1961) as " o p e n " illite. Slake (1950) found gibbsite as a second essential constituent in the kaolinitic underclays rich in titanium (up to 10 percent TiO2) from the Sub-Ore Mountains brown coal basin. A larger number of chemical analyses of Cenomanian kaolinitic claystones from the Bohemian and Moravian Cretaceous strata were published in the works of Vachtl (1950) and Soukup (1954). Konta and Ku~vart (1956) studied the green, blue and white clays from the Cheb basin. They observed that the green clay with predominating illite and a slight admixture of kaolinite swells strongly when brought in contact with water. They also identified kaolinite pM and kaolinite having a structure between kaolinite pM and T. By study of "heavy" and " l i g h t " minerals

CLAY MINEItALS AND ARGILLACEOUS I~OCKS I~q CZECHOSLOVAKIA

429

they have concluded t h a t the source rock of the white kaolinitic clays is the kaolinized granite of Fiehtelgebirge. SpiSs (1957) identifed kaolinite pM as an essential mineral in the Tertiary clays from Kalinovo and Polt~r in Slovakia which are used in the earthenware industry. Sls (1958) studied the mineral composition of silty-Sandy kaolinitic clays from some localities in western Bohemia and discovered kaolinite plY[ as the essential mineral. Cech (1958) studied by differential thermal analysis, X - r a y analysis, chemical analysis and staining tests a larger number of kaolinitic and montmorillonitic clays from a part of the Sub-Ore Mountains brown coal basin. Kukal (1959a, b) found "sericite" as the only clay mineral in Ordoviclan shales of the Barrandian Basin, and in his work special attention was paid to the question of origin of red, gray and green shales and to their chemistry. These argillaceous sediments form approximately one-third of the total bulk of the Ordovician clastic rocks in the Barrandian Basin. Malkovsk~ (1959) discovered t h a t in most parts of the claystones of Carboniferous age in Ostrava Basin illite predominates over kaolinite in the sediments of marine origin, whereas in the freshwater sediments the proportion is the reverse. I n the Upper Cretaceous kaolinitic clays in southern Slovakia, Mi~ik, CiSel and Markov~ (1959) found crystals of kaolinite pM os about 1 m m diameter with holes in the center. High-temperature quartz, idiomorphic crystals and twins of tridymite and a smaller amount of cristohalite are found as admixture in these clays. The source of these clays is considered to be the dacite and rhyolite tuffaceous rocks found in the vicinity. MichaliSek and P}ikryl (1959) studied argillaceous sediments of potential oil areas in Czechoslovakia (mostly of Neocene and 1)aleocene age). I n them they discovered illite as a predominating mineral, and also montmorillonite which is associated with the horizons of tuffaceous material. The sorbed cations of clay minerals were studied by MichaliSek (1959). By means of the cations he postulates the hydrochemical character of sedimentation (whether marine, brackish or freshwater) and makes use of this for solving the stratigraphical problems of the oil-bearing sediments of the northern part of Wien Basin in southern Moravia. Melka and Sls (1959) identified by X-rays some kaolinites T and pM and the intermediate types between these two. Further, they have also studied montmorillonite and irregularly interstratified illite-montmorillonite from Fiiz6rradvs Hungary, where they have found a higher ratio of illite to montmorillonite t h a n is described in the literature.

Laterites and Bauxitic Roc]cs (and Similar Weathering Crusts) The territory of Czechoslovakia, though very rich in kaolin deposits, is poor in bauxitic rocks. The few bauxitic rocks with free aluminum hydroxides t h a t occur in this country contain a considerable admixture of clay minerals; mainly kaolinite and also hematite. The age of the lateritic weathering which has given rise to the primary lateritic profiles and the sedimentary bauxitic rocks of freshwater origin is considered by all authors to be Cretaceous. Vachtl and Konta (1953) studied the geology, petrology and chemistry of

430

TENTH NATIONAL CONFERENCE ON CLAYS AND CLAY MINERALS

the lateritic crust on the biotitic granodiorite of SkuteS. Bauxitic rocks from Rychnov studied by K o n t a (1954a) show great petrologic variations. They contain besides boehmite and hematite a considerable amount of kaolinite and a small admixture of gibbsite; the porous variety contains diaspore. The greenish boehmitic bauxite of Rychnov is one of the rare examples of the rock containing ehamosite of freshwater origin. An analogous chloritic mineral in the form of spherulitic aggregates occurs as a constituent of small reduction spots in bauxite-hematite rock in Marku~ovce, Slovakia (Konta, 1954b). The essential constituents of these clayey-bauxitie rocks are boehmite, kaolinite and hematite. The paper contains numerous chemical and differential thermal analyses. Slhnsk~ (1955) identified pimelite and nepouite among the hydrosilicates of nickel in the weathered crust of a serpentine rock at K~em~e. K o n t a (1958c) studied a bauxite-hematite ore from Ransko and stated t h a t the o61ites differ from the interstitial material only in their higher content of hematite. After removing hematite under reducing conditions in a slightly acidic medium the author identified gibbsite, boehmite and kaolinite. Mat~jka (1958) identified boehmite, gibbsite and hematite in a bauxite from Drienovee. Bentonites

I n recent years new deposits of clay having a high content of montmorillonite were discovered and studied in detail. A large cristobalite content (up to 40 percent by weight) in the montmorillonitie clay from Kuzmice, Slovakia, was determined by K o n t a (1955b). The octahedral deformed crystals of cristobalite reach a size as large as 10 it. This rock had been chemically and thermally studied earlier by Bs ~s and Satava (1949). Chemical and physical properties of montmorillonitie clays containing cristobalite from two new deposits in eastern Slovakia were studied by Gregor and Izs (1959). Gregor, Mass and Mocik (1959) determined the adsorption isotherms of the water solution of methylene blue and basic fuchsine for bentonitie rocks from five deposits in Slovakia. P~ikryl (1959) studied t h e influence of Naphosphates on the stability of Mg- and Na-bentonite suspensions, and he further investigated the relationship between adsorption of these phosphates and the sorbed cations of montmorillonite. Finally he studied a method of separating the ions of alkaline earths from bentonite suspensions. He also ascertained that in suspensions of Mg-bentonite the flocculation ability decreases in the series orthophosphate--tripolyphosphate--hexametaphosphate. Esterka (1959) studied the composition of lignines and their influence on the stability of bentonitic suspensions. H e found t h a t the dispersion properties of the alkaline sulfitolignines increase with the number of electronegative groups in the molecule of the compound (C1, OH, NO 2 and quinoid bonds). The influence of phenols on the colloidal and rheological properties of bentonite suspensions in an alkaline environment was studied b y P~ikryl and Esterka (1960). They concluded t h a t the effects depend firstly on the position and number of hydroxyl groups of the benzene core, and further on

CLAY ~/[INERALS &ND ARGILLACEOUS ROCKS IN CZECHOSLOVAKIA 431

the amount of dipole moment and on the ability to form quinoid bonds in alkaline environments.

Clay Minerals in Sedimentary Iron Ores The silicate iron ores of middle Bohemia were studied in detail microscopically by Slavikovs and Slavik (1917), who described precisely the optical properties of a micaceous flaky mineral which is now identified as illite. I n recent years the data on clay minerals from these ores are becoming more precisely known. Melka (1957a) separated comparatively pure ehamosite of the kaolinite type from Bohemian Ordovician oSlitic ores and studied it by modern methods. Novs and Vt~lensk~ (1960) identified 1 M illite from the same oSlitic iron ores and found that this mineral is an abundant constituent of the tuffaceous rocks underlying the ores. Almost pure polymorphous 1 M modification occurs in the Petrovka locality; monolayer polymorphous modification of illite is found to predominate over montmorillonite structure (1 M illite > montmorillonite) in the Veliz locality. In the low-grade silicate iron ores of Ordovician age Netolicky (1960) found alternating coatings of chamosite and illite in oSlites, and illite was found to predominate in the interstitial material.

Clay Minerals In Carbonaceous Rocks Attention has been paid to the clay minerals found in the carbonaceous rocks of Silurian age which are used as raw material for the production of cement. Konta (1955a) detected illite as the predominating clay mineral in insoluble residues of the Upper Silurian clayey carbonaceous rocks in middle Bohemia. Fine quartz of organic origin is the next most abundant essential constituent of these residues. Some layers contain a small amount of montmorillonite of tuffaceous origin. Kaolinite has been found (along with illite in the approximate ratio 1 : 3) only in the coarse-grained organoclastie limestones that contain very little insoluble residue. The author advocates a terrestrial origin o f these clay minerals as most probable. Kukal (1955) also found illite in the insoluble residues of the Silurian carbonaceous rocks, and only in coarse-grained limestones an admixture of kaolinite.

Clay Minerals of Hydrothermal Origin The study of clay minerals found in hydrothermal veins has been gaining more importance day by day, since the clay mineralogy depicts well the full picture of the hydroehemical and thermal regime of the solutions. The conditions of formation in this natural association are very similar to the conditions under which clay minerals are synthesized in many laboratories. Comparison of these natural and artificial associations of clay minerals helps us to understand with considerable accuracy the conditions of genesis and the thermodynamic stability of clay minerals. In Czechoslovakia much attention has been paid to the study of several magnesium minerals from fissure fillings and clay minerals from ore veins of various types. Konta (1951) identified by microscopic, X-ray, thermal and

432

TENTH NATIONAL CONFERENCE ON CLAYS AND CLAY MINERALS

chemical analysis different varieties of deweylite from the fissure fillings in the serpentine at Mladotice. I n a later study K o n t a and Sindels (1955) found saponite in fissure fillings in amphibolites in the neighborhood of ~s eastern Bohemia. Here the mineral is associated with either albiteoligoclase or calcite, epidote, analcime, laumontite, natrolite and kaolinite in a so-called Alpine paragenesis. The fibrous mineral in fissure fillings in amphibolite from Templ~tejn, Moravia, which was named "parasepiolite" by Fersman (1913), was identified b y K o n t a (1956b) as trioetahedral magnesium illite. Novs et al. (1956) have studied an orthorhombic chamosite from ore veins in K u t n s H e r a found in association with quartz and sulfides of iron, zinc, arsenic and copper. On the same lines as Brindley and Knorring (1954), who have named the orthohexagonal variety of monoclinic antigorite orthoantigorite, these authors have named the orthorhombic chamosite orthochamosite. The orthochamosite from K u t n s Hera, just as the cronstedtite from this locality, has been formed by hydrothermal decomposition of sulfides rich in iron, particularly pyrite and pyrrhotite, and of the silicates from the surrounding gneiss. Sindel~ (1957) has studied the deep-green, kidney-shaped masses of talc from the fissure fillings of an amphibolitie rock near the contact with a peridotitie rock. Novs and K u p k a (1960) found hydromuscovite in the auriferous quartz veins of goudn~, Bohemia. This mineral is made up of a monolayer monoclinic polymorphous modification with a small admixture of 2M 1 structure (1M >~2M1). The clay minerals in the cassiterite-wolframite and molybdenite ore veins of northern Bohemia were studied by Konta (1960d). He found t h a t in the veins t h a t are filled with clay material the three-layer minerals predominate, with predominance of hydromuscovite over montmorillonite. In the open veins, where circulation of hot solutions was easy, dickite containing a small amount of kaolinite predominates and sometimes montmorillonite is present as an admixture. I n further work, K o n t a (1961 b) determined the temperatures of crystallization of these minerals by application of the decrepitation method to the associated quartz, fluorite, topaz and beryl. Kllr (1959) studied the clay minerals from the dislocation planes of various rocks in several types of ore deposits.

Apparatuses for Differential Thermal Analysis and Gravimetric Thermal Analysis Many efforts have been made to simplify and perfect the apparatus for differential thermal analysis (DTA). VaNSek (1954) described the historical development of DTA and referred to the different types of DTA apparatuses. Satava (1957) described a simple, inexpensive, recording thermobalance. Forms and Bauer (1957) published a scheme of a new thermobalance construction with direct registration. Bla~ek (1957) developed an automatic thermobalance with the possibility of simultaneous registration of DTA curves and disintegrating gassy products. Pospi~il and Bers (1957)

CLAY MINERALS AND ARGILLACEOUS ~OCKS IN CZECHOSLOVAKIA 433

constructed a fully automatic apparatus for DTA which differs from the hitherto used apparatuses by a new shape of hollow, pressed sample and by a precise method of checking temperature. Vintera and Bergstein (1957) have recommended a new arrangement of DTA without reference sample, and with the pulverized sample pressed into the shape of a small hollow cylinder having a firm bottom. These authors have recommended the method for recording slight changes in temperature in the sample, especially for some structural changes. Neu~il (1959) constructed an automatic DTA apparatus and explained the main factors influencing the results. Ga~parin, Proks and ~i~ke (1959) constructed an apparatus for rapid DTA with variable heating speed: the temperature of 1000~ is attained during an interval of 90, 60, 45, 30, 15, or only 10 min. A great number of analyses were done in air as well as in a COs atmosphere. Volds (1959) constructed an apparatus for thermal analysis in which the electric conductivity of the finely pulverized samples could be measured using a heating rate of 3-4 ~C/min up to 1000 ~C. The crystallization of new compounds has an influence on the electrical conductivity of the sample. The analysis was used for vitreous samples solidified from melted basaltic rocks but probably can be used also for clay minerals. Satava and Trousil (1960) described a simple construction of an automatic program temperature controller for DTA with the use of semiconductive elements. Vani~ and Kors (1960) constructed a simple apparatus for rapid DTA having a heating rate of 100 ~C/min, suitable for routine laboratory work. Si~ke and Proks (1961) described an instrument for DTA which can record the temperature precisely and can follow the reactions at lower temperatures from - 4 0 to -b 300 ~C. The experimental part of the work is directed towards the study of properties of the water adsorbed by different materials. By means of this instrument they also studied (Proks and Si~ke, 1961) the course of solidification and hardening of cement.

Quantitative MineralogicalAnalysis of Clay Minerals In recent years great emphasis has been laid on quantitative mineralogical analysis. Prochs (1954) presented examples where by means of a thermo: balance constructed by him the quantitative estimation of the kaolinitemontmorillonite clay minerals can be done with an accuracy of 5-10 percent, and the content of sericite in metallurgical quartzites could be determined within an accuracy of 1 percent. K o n t a (1958d) re-examined and applied Vendel's quantitative microscopic analysis for the estimation of very finely dispersed light-coloured minerals in bauxitie rocks after removal of iron oxide pigment. Values of refractive indices of iron-free residues, determined by the immersion method using sodium light, give the bulk percentage of boehmite and kaolinite. Pospi~il (1959) used the exothermie peak of kaolinite for quantitative determination of this mineral in various European kaolins and clays. He also studied the influence of some admixtures on the height of this peak. Proks (1961) explained in a relatively simple way the mathematical relationships 28

434

TENTH NATIONAL CONFERENCE ON CLAYS AND CLAY MINERALS

existing between the constant increase of heating and the factors important in evaluation of DTA curves. One of the seven equations, U. A n H = const "PT, shows the advantage of the curves in which AT ( = temperature difference) depends on the rate of heating, particularly for quantitative determination of a mineral from the area of a suitable peak: U.RH = const.A T (where U = the constant rate of temperature increase in grad/see -1;RH = reaction enthalpy related to the total substance of the analyzed material, in cal. ; A T total area of the peak). Neu~il (1961) prepared artificial mixtures of various clay minerals and dealt with the influence of different factors on the form of the DTA curves of these mixtures. K o n t a (1961 c) has studied by means ofgravimetrie thermal analysis, DTA, and compensation DTA the content of kaolinite in various size fractions of the floated kaolin from Sedlee. ~--

Imbibometric Study Using Water and Organic Liquids In the Petrological I n s t i t u t e of the Charles University a new method was developed b y Konta (1956a) for rapid identification of clay minerals and determination of various physical properties of argillaceous rocks. This method is based on the course of imbibition of a drop of water and a drop of ethylene glycol on ground flat sections of argillaceous rocks. I m b i b o m e t r y is useful not only for identification of clay minerals but also in engineering geology, ceramic technology and other branches where the problems are connected with the mutual effect of the liquid and the porous clay material. In further work K o n t a (1959a, b) has contributed toward the study of total and effective porosity and imbibition capacity of unconsolidated argillaceous rocks of various mineralogical compositions. He has also proposed new diagrams for identification of clay minerals based on this method. I n his recent publication (Konta, 1961) the mathematical explanation of the imbibometric method is given, and in this work the influence of effective porosity and total surface area of the particles on the speed of imbibition of water and ethylene glycol has also been explained. Cimbs163 (1960) and Shrbens (1960) have applied the imbibometric method to identification of clay minerals in loess near Prague.

Problems of Classification and Terminology The complicated problem of classification and terminology of clay minerals and argillaceous rocks is well known. The various authors are influenced by the traditions of their own schools and the literature around them and also, of course, b y their own research work. Kou~imsk~ and ~atava (1954) have contributed towards the classification and terminology of the serpentine group of minerals, not only of mineral species but also varieties. They have given the optical properties and the original DTA curves for most of these minerals. K o n t a (1955c) has found that dillnite from Bansks Bell is a specific mineral and not a mixture of kaolinite and diaspore as hitherto thought. In further work Konta and Mr~z (1961) published more comphrehensive chemical data on dillnite and explained its relation to zunyite.

CLAY MINERALS AND ARGILLACEOUS ~OCKS IN CZECHOSLOVAKIA 435

Melka (1957b) has summarized existing opinions about the classification of chlorites according to chemical and physical points of view. On the request of the Commission for the terminology of minerals, Czechoslovak Academy of Sciences, K o n t a (1958a) has listed and briefly defined the clay minerals for Czechoslovak scientific workers. K o n t a (1958b) has also dealt with the classification and terminology of the rocks in the series bauxite-clay-iron oxide ore. Havlena (1959) has worked out a proposal for a quantitative classification of the rocks in the series coal-argillaceous rock. H e has shown the variations in the terms when the rocks are studied megascopieally on the one hand and microscopically on the other. Mi~ik (1959) has summarized the up-to-date proposals for classification of the rocks in the series clay-carbonaceous rock. K o n t a (1960a, b) has proposed rules for quantitative descriptive classification and terminology of the sedimentary rocks, including the argillaceous rocks. The rules are such that the basic genetic differences in the rocks are perceptible. K o n t a (1960c) has also discussed the schemes of clay mineral classification proposed by Caill~re and tt6nin (1957) and Mackenzie (1959). The author (Konta, 1960c) has named the groups of clay minerals after the best known and most widely occurring mineral, as is usual in the whole mineralogical system, e.g. kaolinite group, montmorillonite group, etc. H e has also recommended that the mineral species be differentiated principally from the varieties and that the structural formulas be written in a uniform way. B~rta (1957) has proposed in collaboration with others a uniform nomenclature and abbreviations in thermography.

Problems of Clay Mineralogy in Ceramic Industry The data of clay mineralogy and petrology are being used more and more in ceramic industry. Bs and Srbek (1954a) published a method for the dressing of loams having a large content of illite and montmorillonite and have shown how they can be used for the mamlfacture of good quality bricks b y mixing the sand available from the floated kaolin. I n a further study Bs and Srbek (1954b) showed the utility of the kaolinitic claystone from the brown-coal basin of northern Bohemia with a content of 42 to 56 percent A120 a and up to about 10 percent Ti02, the essential minerals being kaolinite, gibbsite and anatase. Satava (1954) has discussed the mechanism of hydration of clay minerals and has described a new rapid method for measuring the grade of swelling in argillaceous rocks. Wendler (1954) constructed a useful nomogram for calculating the particle size after Andreasen's equation. Vytasil (1954) studied with the help of a modified Shai:ples supercentrifuge the dispersion curves of the standard kaolin from Sedlec, blue clay from Von~ov containing kaolinite pM in predominance over illite and another kaolinite-illite clay from PoltAr. BabSan (1959) studied the products of thermal decomposition of chloritic minerals having kaolinite structure, i.e. chamosite from Kutns ttora and eronstedtite from P~ibram, and also normal chlorites. During ignition of septeehlorites in a hydrogen atmosphere at 500~ the elementary iron is

436

TE~TH NATIOI~IALCOI~FERENCE ON CLAYS AI~D CLAY MINERALS

liberated, a n d spinel [(FeO. MgO). A1203] and q u a r t z are formed. The element a r y iron is n o t liberated from n o r m a l chlorites b u t is b o u n d i n MgO. (F%O a 9 A1203). These results can have considerable i m p o r t a n c e for the problem of the character of the d e h y d r o x y l a t i o n product of kaolinite. BabSan presumes from this t h a t at the t e m p e r a t u r e given, t h e r m a l decomposition i n t o amorphous oxides takes place, a n d no c o m p o u n d analogous to m e t a k a o l i n arises. S a t a v a (1961) has summarized t h e various opinions regarding the reactions t a k i n g place when kaolinite is heated to a t e m p e r a t u r e higher t h a n 1200 ~ C. Miscellaneous Studies

Stovik a n d Melka (1959) constructed a new a p p a r a t u s for d e t e r m i n a t i o n of refractive i n d e x b y the b i v a r i a t i o n m e t h o d directed especially toward clay m i n e r a l study. K o n t a (1959c) has dealt with the question of working on clay minerals u n d e r c o n s t a n t l a b o r a t o r y t e m p e r a t u r e a n d h u m i d i t y conditions. For b e t t e r differentiation of the c o n t e n t of molecular water a n d h y d r o x y l water i n a n y clay material he has r e c o m m e n d e d t h a t every published chemical analysis should be a c c o m p a n i e d b y a gravimetric t h e r m a l curve. P~ikryl a n d KrajSa (1960) constructed a n a p p a r a t u s for m e a s u r e m e n t of electrophoretic m o b i l i t y (~-potential) of clay particles. This a p p a r a t u s is constructed more simply t h a n the well-known a p p a r a t u s of Tiselius. As a n example, the course of stabilization of a W y o m i n g b e n t o n i t e suspension has been m e a s u r e d on this i n s t r u m e n t . REFERENCES Bab6an, J. (1959) Contribution to the problem of products of thermal decomposition of minerals with kaolinite structure: Silikdty, Prague, v. 3, pp. 20-25. Bab~rek, J., Konta, J. and Svoboda, D. (1959) Petrographical investigation of the Karlovy Vary kaolin from Otovicc: Acta Univ. Carolinae, Geologica, pp. 171-195. B~rta, R. (1930) Nontronite earth from Oslavany in Moravia: Zprdvy ~s. Keram. Spol., Prague, v. 7, pp. 68-73. Bhrta, 1~. (1957) Nomenclature and abbreviations of thermography: Silikdty, Prague, v. 1, pp. 191-192. Bhrta, R., LAp, M. and ~atava, V. (1949) On metabentonite and halloysite in Slovakia: Zprdvy Ust. Skld~., Keram. etc., Prague, v. 10, pp. 1-13. B&rta, R., ~atava, V., Vachtl, J. and Vaw J. (1950) Green clay from Vonw Zprdvy Ust. Skld~., Keramiky etc., v. 11, pp. 1-18. B&rta, R. and Srbek, F. (1954a) Some experiences with montmorilloniticloams in brick industry: Sborntk Praci z Technol. Silikdt4, Prague, v. 1, pp. 7-12. Bs R. and Srbek, F. (1954b) Ceramic use of the North-Bohemian clays: Sbornl]c Pracl z Technol. Silikdt4, v. 1, pp. 13-17. Bla~ek, A. (1957) Thermobalance with electromagnetic compensation of weight variations: Silikdty, Prague, v. l, pp. 158-163. Breithaupt, A. (1838) Bestimmung neuer Mineralien: J. Prakt. Chemic, v. 15, p. 325. Brindley, G. W. and Knorring O. yon (1954) A new variety of antigorite (orthoantigorite) from Unst, Shetland Islands: Amer. Min., v. 39, pp. 794-804. Bukovsk:~, A. (1906) Minerals from serpentine of Kutn& i o r a : V~ro~. Sprdva Redl. v K. Ho~e (spec. reprint), p. 1-22. Caill~rc, S. and Hdnin, S. (1957) Propositions pour normaliser la nomenclature des mingraux argileus: Bull. Groupe Franc. des Argiles, v. 9, pp. 77-83.

CLAY MINERALS AND ARGILLACEOUS I:~OCKS IN CZECHOSLOVAKIA

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Cech, F. (1958) Mineralogical s t u d y of some clays from Sokolovo-Loket brown coal basin: Rozpravy CSA V, series M P V , v. 68, se[it 1, pp. 29-60. Cimbs A. (1960) Petrographical investigation of loess sediments in Sedlee n e a r Prague: Dipl. :Dissertation, Prague, p. 206. Dittler, E. a n d Hibsch, J. E. (1923) Ueber A n a u x i t a n d Cimolit y o n Biliu: Tscherm. M P M , v. 36, pp. 85-92. Esterl,a, F. (1959) Chemisehe Eigenschaften von Ligninen u n d deren Einfluss a u f physikalisch chemisehe Eigenschaften tier Bentonite : Acta Univ. Carolinae, Geologica, pp. 87-99. F e r s m a n , A. E. (1908) Materials to the s t u d y of palygorskite group : Izvestya Akad. Nauk, ser. 6, t o m II, no. 8, pp. 637-666. F e r s m a n , A. E. (1912) On fibrous asbestos of Bohemia a n d Moravia: Rozpravy ~eskd Akad., II. t~., Prague, v. 21, no. 15, pp. 1-4 (spec. reprint). F e r s m a n , A. E. (1913) Investigation in the field of the m a g n e s i u m silicates of the zillerite, zermattite a n d palygorskite group: Zapiski Akad. Nauk, ser. 8, v. 32, no. 2. (Also: Izbranniye Trudi, t o m I, Izv. A N S S S R , p. 862, Moscow, pp. 340-341.) Forms Z. a n d Bauer, J. (1957) Thermobalance with direct registration: Silikdty, v. 1, pp. 164-170. Ga[parln, C., Proks, I. a n d ~i~ke, V. (1959) Method of accelerated differential t h e r m a l analysis: Silikdty, v. 3, pp. 64-73. Gregor, M. and I z i k o v l , K. (1959) Slowakische aktive Erden: Chemickd Zvesti, S A V, Bratislava, v. 13, pp. 326-337. Gregor, M., Mass J. a n d Mocik, S. (1959) Adsorptfonsisothermen einiger slowakischen aktiven Erden : Chemickd Zvesti, S A V, v. 13, pp. 524-529. Haidinger, W. ( 1861) Jahresbericht der Geol. Reichsanstalt (Verhandl.), Wien, v. 12, p. 74. Havlena, V. (1959) Die T y p e n der Ablagerungen aus der Reihenfolgo K o h l e - - t o n i g e s Gestein (Ein E n t w u r f der makro- u n d mikropetrographischen Klassifikation): Acta Univ. Carolinae, Geologica, pp. 111-123. Hibseh, J. E. (1930) Geologischer t~i~hrer dutch das Bfihmische Mittelgebirge, Berlin, p. 363. Hibseh, J. E. (1934) Die Minerale des Bghmischen Mittelgebirges: Jena, pp. 166-170. Jarka, J. (1947) On the mechanical composition a n d t h e base exchange in bentonite from Brafiany: Rozpravy I I . t~. ~eskd Akad., Prague, v. 57, no. 11, pp. 1-15 (spec. reprint). Kallauner, O. J n . (1949) Investigation of halloysite from Michalovee in Czechoslovakia: Stavivo, Brno, no. 16 20 (spcc. reprint) pp. 1-50. Kallauner, O. a n d Bs R. (1918) On p r i m a r y kaolins from Moravia: Zprdvy Ces. Svazu pro V~zkum a Zkou~. Techn. D~deS. Ldtek, Prague-Brno, v. 1, odbor 2, pp. 7-13. Kallauner, O. a n d Mat~jka, J. (1926) On some properties of t h e kaolin from U n a n o v : Stavivo, v. 7, p. 582. Katzer, F. (1894) Beitri~ge zur Mineralogie BShmens : Tscherm. M P M , v. l, pp. 483-525. K e n n g o t t , A. (1878) Ueber den U n g h v a r i t , Nontronit, P o l y d y m i t : B., Neues Jahrb. f. Min. etc., pp. 180-185. Klaproth, A. (1795) Beitr~ige zur Chemischen Kenntniss der MineralkSrper: Bd. I, p. 291. Klir, S. (1959) Die U n t e r s u c h u n g yon tonhaltigen Mineralien in der Ausfiillung y o n StSrungen u n d die B e d e u t u n g derselben ffir die bergbauliehe Praxis: Acta Univ. Carolinae, Geologica, pp. 227-232. K o n t a , J. (1951) Investigation of the deweylites from t h e fissure fillings in the serpentine of Mladoticc: Bull. Intern. Acad. Tchdque des Sei., v. 52, no. 31, pp. 1-13. K o n t a , J. (1954a) Contribution to t h e petrography a n d genesis of the b a u x i t e of l~ychnov: Acta Univ. Carolinae, Geologica, pp. 37-63. Konta, J. (1954b) Petrographical a n d chemical investigation of the bauxites of Marku~ovce (Eastern Slovakia): Rozpravy CSA V, J~ada M P V . , v. 64, sew 4, pp. l 1-64. K o n t a , J. (1955a) Clay minerals and free silica in the carbonate sediments of the Silurian of Bohemia: Universitas Carolina, Geologica, v. 1, pp. 29-70.

438

TENTH NATIONAL C01~FERElqCE O17 CLAYS Al~D CLAY MINERALS

Konta, J. (1955b) Montmorillonite and cristobalite in the clay of Kuzmice (eastern SIovakia): Universitas Carolina, Geologica, v. 1, pp. 165-176. Konta, J. (1955c) Dilinit--ein spezifisches Tonmineral.: Chemic der Erde, v. 17, pp. 223232. K o n t a J. (1956a) Schnelle petrographisehe Identifikation der Tonminerale in den Anschliffen rnittels Wasser und Ethylcnglykoll: Cheraie der Erde, v. 18, pp. 179-193. Konta, J. (1956b) Trioctahedral illite from Tcmplw in western Moravia (Fersman's "parasepiolite"): Izvestya Akad. N a u k S S S R , ser. geol., no. 11, pp. 109-113. Konta, J. (1957) Clay minerals of Czechoslovakia: Naklad. CSA V, Monography, Prague, 319 pp. Konta, J. (1958a) A list of clay minerals and their brief definitions : Acta Univ. Carolinae, Geologica, pp. 163-174. Konta, J. (1958b) Proposed classification and terminology of rocks in the series bauxiteclay-iron oxide ore: J. Sed. Petrology, v. 28, pp. 83-86. K o n t a J. (1958c) Petrography and origin of bauxitic hematite ore from Ransko (Eastern Bohemia): Acta Univ. Carolinae, Geologica, pp. 29-45. K o n t a J. (1958d) Semiquantitative microscopic determination of alitic and sialitic minerals in bauxitie rocks : Silikdty, v. 2, pp. 149-156. Konta, J. (1959a) Porosity of clay rocks and their imbibition capacity: Silicates Industriels, Brussels, v. 24, pp. 133-136. Konta, J. (1959b) Porosity and imbibition capacity of unconsolidated rocks: Acta Univ. Carolinae, Geologica, pp. 25-43. Konta, J. (1959c) Investigation of clay minerals under constant laboratory working conditions: Silikdty, v. 3, pp. 239-246. Konta, J. (1960a) Petrographical classification and terminology of sedimentary rocks. I. Contemporaneous state in classification and terminology of sedimentary rocks : Acta Univ. Carolinae, Geologica, pp. 241-255. Konta, J. (1960b) Petrographical classification and terminology of sedimentary rocks. II. Classification of great basic groups of sedimentary rocks: Acta Univ. Carolinae, Geologica, pp. 257-268. Konta, J. (1960c) Remarks to the classification and terminology of clay minerals: Sililcdty, v. 4, pp. 332-338. Konta, J. (1960d) Clay minerals from cassiterite-wolframite and molybdenite ore veins in K r u p k a (Graupen): Aeta Univ. Carolina,, Geologica, pp. 23-50. Konta, J. (1961a) I m b i b o m e t r y - - a new method for the investigation of clays: Amer. Min., v. 46, pp. 289-303. Konta, J. (1961b) Crystallization temperatures of clay minerals in the molybdenite and cassiterite-wolframite ore veins of northern Bohemia : Gen~se et Synthdse des Argiles, CoUoques Interv~t. du Centre Nat. de la Recherche Sci., Paris, no. 105 (Spot. reprint), pp. 1-8. Konta, J. (1961c) The content of kaolinite in fractions of different size of the floated kaolin from Sedlec: Acta Univ. Carolinae, Supplementum, 2nd Conference on Clay Mineralogy and Petrography, Prague (in press). :Konta, J. and Ku~vart, M. (1956) Die petrographische Untersuchtmg der Serie keramischer Tone aus dem Cheber (Egerer) Becken: Universitas Carolina, Geologica, v. 2, pp. 171-199. Konta, J. and Mrs L. (1961) Dillnite and its relation to zunyite: Amer. Min., v. 46, pp. 629-636. Konta, J. and Pouba, Z. (1961) Excursion guide (Second Conference on Clay Mineralogy and Petrography, Prague) : Publication of the Charles University, 50 pages. Konta, J. and ~indel~, J. (1955) Saponitc from the fissure fillings in the amphibolites of ~s Universitas Carolina, Geologiea, v. 1, pp. 177-186. Kou~imsk~, J. and ~atava, V. (1954) A contribution to the question of the determination of minerals of serpentine group : Acta Musei Nationalis Pragae, v. 10, B, no. 4, Mineralogia no. 1, pp. 1-19.

CLAY MINERALS A N D ARGILLACEOUS ~OCKS IN CZECHOSLOVAKIA

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Kovfi~, F. (1896) C h e m i c M i n v e s t i g a t i o n of five M o c a v i a n m i n e r M s : Rozpravy I1. t~. ~eskd Akademie, v. 5, no. 15, pp. 1-18. K o v ~ , F. (1898a) A n a l y s e s of s o m e m i n e r a l s f r o m g r a p h i t e m i n e s a t Mal:~ T r a s h y , M o r a v i a : ~asopis pro PrCtmysl Chem., Prague, v. 8, pp. 1 - 4 (spec. reprint). Kovhf', F. (1898b) C h e m i c a l i n v e s t i g a t i o n of s o m e m i n e r a l s f r o m t h e v i c i n i t y of M o r a v s k s Ole~nice: Rozpravy Ces. Akademie, Prague, v. 7, no. 9, (Ref. Neues Jahrb. f . Min., etc. (1900) Bd. 1, p. 24.) Kovs F. (1899) O n t w o h e a t - r e s i s t i n g learns f r o m V r a n o v 6 n e a r I ~ e t i n in M o r a v i a : ~asopis pro PrCtmysl Chem., v. 9, p. 211. Kovh~, F. (190 l a) A n a l y s e s of four m i n e r a l s f r o m w e s t e r n M o r a v i a : Listy Chem., Prague, p. 233 (Ref. Neues Jahrb. f. Min., etc., Bd. 1, p. 402). Kovs F. (1901b) A c o n t r i b u t i o n to t h e k n o w l e d g e o f c o m p o s i t i o n of t h e bole g r o u p :

Vgstn~k I I I . Siezdu &s. Ldlca~'u a P~irodov~der

~asop. pro PrCtmysl Chem., Prague,

p. 225. Kovs F. (1902-3) C h e m i c a l - m i n e r a l o g i c a l reports: V~r. Zprdvy Cs. Akad. Obchodnl, P r a g u e , v. 31, pp. 1-13 (spar. reprint). Kratochv61, J. (1927) R e m a r k s on t h e p e t r o g r a p h y a n d m i n e r a l o g y of K l a d n o Carboniferous rocks: Vgstn4tc Stdt. Geol. ~. OSR, Prague, v. 3, no. 6, pp. 217-231. K u k a l , Z. (1955) A p e t r o g r a p h i c a l i n v e s t i g a t i o n of K o p a n i n a beds et~1 in t h e w e s t e r n p a r t of t h e Silurian of t h e B a r r a n d i a n : Universitas Carolina, Geologiea, v. l, pp. 71-110. K u k a l , Z. (1959a) A p e t r o g r a p h i c a l i n v e s t i g a t i o n of t h e K l a b a v a beds of t h e O r d o v i c i a n of t h e B a r r a n d i a n : Sbornlk ~)UG, v. 25, geol. ser., p p . 7-80. K u k a l , Z. (1959b) A p e t r o g r a p h i c a l i n v e s t i g a t i o n of t h e O r d o v i e i a n argillaceous sedim e n t s of t h e B a r r a n d i a n : Aeta Univ. Carolinae, Geologica, pp. 125-140. K u k l a , J . (1959) Geologic der K a r l s b a d e r K a o l i n l a g e r s t ~ t t e n : Aeta Univ. Carolinae, Geologica, pp. 141-170. K u ~ v a r t , M. (1960) A p r e l i m i n a r y r e p o r t on geologic r e l a t i o n s of t h e kaolin d e p o s i t s in Moravia-Silesia: Vgstnlk U[?G, v. 35, pp. 399-401. Mackenzie, R. C. (1959) T h e classification a n d n o m e n c l a t u r e of clay m i n e r a l s : Clay M i n . Bull., v. 4, pp. 52-66. Malkovsk:~, M. (1959) Clay m i n e r M s of " O s t r a v a beds " : Acta Univ. Carolinae, Geologica, pp. 197-210. Matj~ka, A. (1958) O c c u r r e n c e of t h e b a u x i t i c rocks f r o m D r i e n o v e c in s o u t h e r n S l o v a k i a : Vgstnlk UL?G, v. 33, p p . 279-281. Melka, K . (1957a) C h a m o s i t e f r o m oSlitie iron ores of B o h e m i a n O r d o v i e i a n r o c k s : Sbornik k Osmdesdtindm Akad. F. Slavlka, Naklad. ~ S A V, Prague, p p . 255-286. Melka, K . (1957b) O p i n i o n s a b o u t t h e classification of chlorites: Casopis pro Mineralogii a Geologii, v. 2, pp. 58-67. Melka, K . a n d Sl~nsk~r, E . (1959) U e b e r die A n w e n d u n g d e r G u l n i e r - K a m e r a n a e h P.M. de Wolff fiir die r S n t g e n o g r a p h i s c h e U n t e r s u c h u n g der T o n m i n e r a l i e n : Acta Univ. Carolinae, Geologiea, pp. 3-24. MichaliSek, M. (1959) S o r b e d c a t i o n s of c l a y s e d i m e n t s - - i n d i c a t o r s o f t h e h y d r o e h e m i c a l conditions of s e d i m e n t a t i o n : Acta Univ. Carolinae, Geologiea, pp. 61-72. MichMiSek, M. a n d P N k r y l , J. (1959) Die T o n s e d i m e n t e der erdSlhSfflgen Gebiete d e r T s e h e c h o s l o v a k i s c h e n R e p u b l i k u n d ihre B e d e u t u n g in d e n E r d S l u n t e r n e h m e n : Aeta Univ. Carolinae, Geologica, pp. 211-226. Miw M. (1959) E n t w u r f einer einheitlichen K l a s s i f i k a t i o n u n d T e r m i n o l o g i e v o n g e m i s c h t e n k a r b o n a t i s e h e n G e s t e i n e n : Geologic~d Prdee, Zprdvy, Bratislava, v. 16, pp. 61-78. Mi~ik, M., CiSel, B. a n d Markov~, M. (1959) M i n e r a l o g i s c h - p e t r o g r a p h i s c h e A n a l y s e u n d Genesis der T o n e des k l e i n e n L i g n i t b e c k e n s y o n P u k a n e c : Acta Univ. Carolinae, Geologiea, pp. 101-109. Netoliekj~, J. (1960) T h e p e t r o g r a p h i c r e s e a r c h of t h e ~ r k a b e d s a t t h e iron ore d e p o s i t A n t o n de P a d u a in K l a b a v a n e a r Pilsen: Acta Univ. Carolinae, Geologica, pp. 153-170. Neu~il, J. (1959) A u t o m a t i c device for differential t h e r m a l a n a l y s i s a n d its f u n c t i o n : Acta Univ. Carolinae, Geologica, pp. 45-59.

440

T E N T H I~ATIONAL CONFERENCE ON CLAYS AND CLAY MINElCALS

RTeu~.il, J . (1961) A q u a n t i t a t i v e e s t i m a t i o n of kaolinite w i t h t h e help of D T A : Acta

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CLAY MINERALS AND ARGILLACEOUS I:~OCKS IN CZEGI~IOSLOVAKIA

441

R e u s s , A. E. (1840) Geogno~'tische Skizzen aus B6hmen. L B a n d , P r a g - T e p l i t z , pp. 2 2 1 225. ~ a t a v a , V. (1949) On t h e mineralogical c o m p o s i t i o n a n d s o r p t i o n c a p a c i t y of c e r a m i c e a r t h s : Zprdvy Ustavu Slcld~. a Keramiky, etc., :Prague, v. 7, pp. 1-26. ~ a t a v a , V. (1954) C o n t r i b u t i o n to t h e s t u d y of t h e h y d r a t i o n of clay m i n e r a l s : Sbornik Prael z Technol. Sili~dt~, P r a g u e , v. 1, pp. 155-160. ~ a t a v a , V. (1957) Simple r e g i s t r a t i n g t h e r m o b a l a n c e : Silikdty, v. 1, p p . 188-190. ~ a t a v a , V. (1961) T h e t h e r m a l d e c o m p o s i t i o n of kaolinite : Silikdty, v. 5, pp. 248-255. ~ a t a v a , V. a n d Trousil, Z. (1960) Simple c o n s t r u c t i o n of a p p a r a t u s for a u t o m a t i c D T A : Sili~dty, v. 4, pp. 272-277. Schrauf, A. (1877) N e u e M i n c r a i v o r k o m n i s s e i m G r a p h i t v o n M u g r a u , B S h m e n : Neues Jahrb. f. Min., etc., pp. 251-257. Shrben~, B. (1960) P e t r o g r a p h i c a l i n v e s t i g a t i o n of s e d i m e n t a r y rocks in a brick-kiln in :Prague-Kobylisy: Diplom. Dissert., 147 pp. ~ i n d e l ~ , J. (1957) K i d n e y talc f r o m t h e q u a r r y :Peklo n e a r t t a b r y : Universitas Carolina, Geologica, v. 3, pp. I07-114. ~i~ke, V. (1950) C o m p o s i t i o n a n d p r o p e r t i e s of u n d e r e l a y s in t h e : N o r t h - B o h e m i a n b r o w n coal b a s i n : Stavivo, v. 28, no. 17, p. 269. ~iw V. a n d P r o k s , I. (1961) Some possibilities of t h e a p p l i c a t i o n of D T A a t low t e m p e r a t u r e s : Silikdty, v. 5, pp. 142-148. Sl&nsk#, E. (1955) A c o n t r i b u t i o n to t h e k n o w l e d g e of t h e N i - h y d r o s i l i c a t e s f r o m Kf'em~e in S o u t h e r n B o h e m i a : Universitas Carolina, Geologica, v. 1, pp. 1-28. Sl~nsk~, E. (1958) T h e m i n e r a l c o m p o s i t i o n of p a i n t e r ' s e a r t h s a n d ochres f r o m s o m e localities in W e s t e r n B o h e m i a : Rozpravy C S A V , set. M P V , Prague, v. 68, no. 1, pp. 61-78. Slavikov~, L. a n d Slavik, F. (1917) S t u d y on iron ores of t h e B o h e m i a n Lower Silurian: Rozpravy Ceskd A~ad., I I . t~., Prague, v. 26, no. 62, pp. 1-50 (spec. reprint). Sokol, R . (1921) O n a n e w m e t h o d d e t e r m i n i n g t h e a m o u n t of t h e finest particles in e a r t h s : Zemgdglsk~ Archiv, Prague, v. 12, no. 3-6, pp. 1-39 (spec. reprint). S o u k u p , J . (1954) T h e d e p o s i t s of C e n o m a n i a n claysl~oncs in B o h e m i a a n d M o r a v i a : Geotechnica, Naklad, CSA V, Prague, P t . I I , 179 p p . ~piS~k, K . (1957) C o n t r i b u t i o n to t h e s t u d y of clays f r o m Ipel V a l e y : Sbornilc Praei z Technol. Silikdt~t, v. 3, pp. 206-215. ~plichal, J. (1921-22) O n t h e h y g r o s c o p i e i t y of t h e k a o l i n a n d t h e soil m i n e r a l s : Sbornik St. GU, Prague, v. 2, pp. 17-24. ~{ovik, M. a n d Melka, K . (1959) D e t e r m i n a t i o n of r e f r a c t i v e i n d e x b y m e a n s of d o u b l e v a r i a t i o n m e t h o d : Acta Univ. Carolinae, Geologica, pp. 233-244. V a c h t l , J. (1950) T h e d e p o s i t s of C e n o m a n i a n c l a y s t o n e s in B o h e m i a a n d M o r a v i a : Geotechniea, Prague, :part I, Na&lad CSA V, 72 p p . V a e h t l , J . a n d K o n t a , J . (1953) T h e laterite f r o m SkutiSko in t h e I r o n M o u n t a i n s : 5~bornilc UUG, v. 20, odd. geol. pp. 577-592. Vanig, M. a n d K o r s O. (1960) A s i m p l e a p p a r a t u s for t h e r a p i d D T A : Sililcdty, v. 4, pp. 266-271. Va~i6ek, J. (1954) Differential t h e r m a l a n a l y s i s a n d its u s e for identification of m i n e r a l c o m p o s i t i o n of c e r a m i c r a w m a t e r i a l s : Sbornlk Praci z Technol. Sili]cdt~t, Prague, v. 1, pp. 57 75. Vintera, J . a n d B e r g s t e i n , A. (1957) A r r a n g e m e n t of differential t h e r m a l a n a l y s i s w i t h o u t reference s a m p l e : Silikdty, v. 1, p p . 94-97. Voids J. (1959) Electric t h e r m a l a n a l y s i s of m e l t e d rocks: Silikdty, Prague, v. 3, pp. 1-13. Vytasil, V. (1954) D e t e r m i n a t i o n of t h e size of m i c r o p a r t i c l e s in ceramic e a r t h s b y a s u p e r c e n t r i f u g e of S h a r p i e s ' t y p e : Sbornik Prael z Technol. Sililcdt~, v. 1, pp. 118-122. W e n d l e r , L. (1954) A n o m o g r a m for t h e c o m p u t a t i o n of particle size after A n d r e a s e n : Sborn4k Prctei z Technol. Sililcdt~t, v. 1, pp. 115-117.

442

TENTH NATIONAL CONFERENCE ON CLAYS AND CLAY MINERALS

Zartner, W. R. (1932) Westb6hmische Kaolin- und Tonlagerst/~tten: Zprdvy (~s. Keram. Spol., Prague, v. 9, pp. 61-75, Zartner, W. I~. (1934) Die T o n v o r k o m m e n i m Egerer Ter~ii~rbecken: Schldgel u. Eisen, Teplitz-Sch6nau, pp. 1-20 (Sonderdruek). Zepharowich, V. (1853) Ueber einige interessante Mineral-Vorkommen yon Mut/~nitz bei Strakonitz in B 6 h m e n : Jahrb. d.k.h~. Geol. Reichsanstalt, v. 4, pp. 695 700.