ROCK IDENTIFICATION LAB

What type of rock is this? Where or how is it formed?

Obsidian  Mafic (black) 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  Mafic Extrusive Igneous Rock  Fine grained (some small crystals)  Formed from dark dense lava  Pyroxene, plagioclase feldspar

What type of rock is this? Where or how is it formed?

Scoria  Mafic Extrusive Igneous Rock  No crystals formed  Forms as a frothy crust on the top of a lava flow or as material ejected from a volcanic vent and solidifying while airborne  Many holes formed - gasses released

What type of rock is this? Where or how is it formed?

Pumice  Felsic Extrusive Igneous Rock  No crystals formed  Quick cooling molten rock (lava)  Many holes formed - gasses released  Floats on water

What type of rock is this? Where or how is it formed?

Granite  Felsic 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  Clastic Sedimentary Rock  Thin, dark gray sheets – easily broken  Formed from mud and clay being pressed together

Image Source What type of rock is this? Where or how is it formed?

Sandstone  Clastic Sedimentary Rock  Light red/dark pink with very small pieces of sand  Quartz cemented by silica or lime  Most form in shallow seas

Image Source What type of rock is this? Where or how is it formed?

Coal  Organic Sedimentary Rock  Black, smooth and lightweight  Formed from layers of plant remains that are pressed together over time

Image Source What type of rock is this? Where or how is it formed?

Limestone  Organic Sedimentary Rock  Calcium Carbonate - calcite  Forms from the accumulation of shell, coral, and fecal debris in clear, warm, shallow marine waters

What type of rock is this? Where or how is it formed?

Conglomerate  Clastic 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? Where or how is it formed?

Hornfels  Metamorphic Rock  Non-foliated  Fine grained crystals  Metamorphism of clays or Shales

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