What type of rock is this? Where or how is it formed?
Breccia (volcanic)
Extrusive Igneous Rock Quick cooling molten rock (lava) Like “rubble” Broken fragments of minerals or rock cemented together with fine-grain ash/dust from the volcano
What type of rock is this? Where or how is it formed?
Obsidian
Extrusive Igneous Rock No crystals formed Glassy Very quick cooling molten rock (lava)
What type of rock is this? Where or how is it formed?
Basalt
Extrusive Igneous Rock Fine grained (some small crystals) Formed from dark dense lava
What type of rock is this? Where or how is it formed?
Pumice
Extrusive Igneous Rock No crystals formed Quick cooling molten rock (lava) Many holes formed - gasses released Floats on water
What type of rocks are these? Where or how are they formed?
Granite
Intrusive Igneous Rock Coarse Grained - can see crystals Contains quartz and feldspar
What type of rock is this? Where or how is it formed?
Shale
Sedimentary Rock Thin, dark gray sheets – easily broken Formed from mud and clay being pressed together
What type of rock is this? Where or how is it formed? Image Source
Sandstone
Sedimentary Rock Light red/dark pink with very small pieces of sand Quartz cemented by silica or lime Most form in shallow seas
What type of rock is this? Where or how is it formed? Image Source
Coal
Organic Sedimentary Rock Most coal (“soft coal”/bituminous) is sedimentary (typically has bright and dull bands) “Hard coal” (anthracite) is metamorphic (has a bright luster)
Black, smooth and lightweight Formed from layers of plant remains that are pressed together over time
What type of rock is this? Where or how is it formed? Image Source
Limestone
Organic Sedimentary Rock Calcium Carbonate - calcite Forms from the accumulation of shell, coral, and fecal debris in clear, warm, shallow marine waters
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Conglomerate
Sedimentary Rock Red with rounded pebbles cemented together Formed near moving water
What type of rock is this? Where or how is it formed?
Quartzite
Metamorphic Rock Non-Foliated Individual quartz grains have recrystallized but are too small too see Metamorphism of Sandstone
What type of rock is this? Where or how is it formed?
Marble
Metamorphic Non-Foliated Made of mostly small to medium sized calcite crystals Metamorphism of Limestone
What type of rock is this? Where or how is it formed?
Gneiss
Metamorphic Foliated – pink and grey alternating bands Medium to coarse grained texture Metamorphism of Granite
What type of rock is this? Where or how is it formed?
Slate
Metamorphic Rock Foliated Breaks into thin “slices” Metamorphism of Shale
What type of rock is this?
Sedimentary (coquina limestone)
Rock or Mineral?
Mineral (muscovite mica)
Comparisons
Basalt vs. Slate Both
dark colors Basalt is igneous and Slate is metamorphic
Pumice vs. Basalt Both
igneous made of quick cooling lava (extrusive) Pumice is felsic and Basalt is mafic
Granite vs. Gneiss Both
have course grains/crystals Granite is igneous and Gneiss is metamorphic
Comparisons
Scoria vs. Pumice Both
are porous (have air bubbles/holes) Scoria is mafic and Pumice is felsic
Obsidian vs. Coal Both
are black, no crystals Obsidian is igneous and Coal is sedimentary
Marble vs. Limestone Both
are made of calcite Marble is metamorphic and Limestone is sedimentary
Comparisons
Slate vs. Shale Both
thin slices, made of mud and clay, dark color Slate is metamorphic (morphed from shale), Shale is sedimentary
Hornfels vs. Slate Both
metamorphic rocks made from Shale Hornfels is not foliated and Slate is foliated
Sandstone vs. Quartzite Both
grainy and made of Quartz Sandstone is sedimentary and Quartzite is metamorphic
Comparisons
Limestone vs. Marble Both
are made of calcite Limestone is sedimentary and Marble is metamorphic
Conglomerate vs. Limestone Both
sedimentary rocks formed in or near water Conglomerate is clastic (made of pebbles cemented together by moving water) and Limestone is organic (made of shell coral, fecal debri found in shallow water)
Gneiss vs. Granite Both
contain course grain crystals Gneiss is metamorphic and Granite is igneous
Comparisons
Quartzite vs. Sandstone Both
contain the mineral Quartz Quartzite is metamorphic (pressure and heat), Sandstone is sedimentary (cemented together by water + sandstone or lime)
Coal vs. Obsidian Both
are black and smooth and contain no crystals Coal is sedimentary and Obsidian is igneous
Shale vs. Slate Both
made of mud and clay (Slate is made from Shale) Shale is sedimentary and Slate is metamorphic
