Rocks! Flashcards
Granite
Igneous
coarse grained
primarily orthoclase and quartz, with biotite and hornblende
Mainly yellowish white, lightly speckled with large black bits (reflective)
(like syenite but more quartz present)
Syenite
Rock
Igneous
coarse grained
primarily orthoclase, with biotite and hornblende
light grey rock with lots of dark small specs (reflective)
Rhyolite
Igneous
fine grained
primarily orthoclase and quartz, with biotite and hornblende
pinkish-brown with random reflective specs
Gabbro
Igneous
coarse grained
Mainly pyroxenes with plagioclase
predominately black with grey and white specs (reflective)
Basalt
Igneous
fine grained
Mainly pyroxenes with plagioclase
Black (dull)
Obsidian
Igneous
Glassy
Mix of orthoclase, quartz, plagioclase, biotite, and hornblende
Black and glassy!!
Gneiss
Metamorphic
coarse, medium, and fine
mainly quartz, feldspar, and micas
made from granite
colored banding!!
Phyllite
Metamorphic
fine granular
clay (not noticeable) and mica (noticeable)
silky sheen, splits with flakes, thin layers, grey with yellowish white
Marble
Metamorphic
coarse to fine
calcite, dolomite, serpentines
made from limestone
Blend of colors (no speckling, more like gradients). observed rock is mix of white, orange, and brown
Slate
Metamorphic
fine granular
minerals not visible
made from shale
smooth cleavages, thin layers, smoother than shale. Observed rock is dark grey
Schist
Metamorphic
coarse, medium, fine
mainly schist with mica
mica is super noticeable (very reflective). Color is tan with grey/black speckling (layers on side)
Shale
Sedimentary
fine
made of silts and clays
often grey, can be white, red, green, or black
White Sandstone
Sedimentary
Coarse
main component is quartz
Very sadly and crumbly, light color
Limestone (Calcitic)
Sedimentary
Fine
high amounts of calcium carbonate
dark grey with rust colored patches
Limestone (Dolomitic)
Sedimentary
Fine
high amounts of calcium carbonate
yellow with rust colored patches
Conglomerate
Sedimentary
Very coarse
consists of gravels and usually in aqueous environments
Collection of small stones morphed together into this rock
Rock
2+ minerals mixed by geological processes in varying proportions
Igneous
Formed by cooling and consolidation of molten rock (magma)
Visible crystals may be present
Slower the cooling, the coarser the texture (more crystals)
No stratification, banding, or lamination
Metamorphic
Previously formed rocks altered physically and chemically by heat and pressure
crystals may be banded(!!!)(2+ minerals alternating)
distorted crystals
laminations or foliations (thin layering)
Sedimentary
Formed from weathered rocks being cemented together
Stratification or layering (layering of sediments)
No crystals
Reaction of HCl with calcitic vs dolomitic limestones
Calcitic- freely fizzes
Dolomitic- fizzes slowly (tiny bit)
Limestone has CaCO3 (calcium carbonate) that reacts with HCl acid to form CO2 (bubbles)
Non-carbonates (sandstone and shale) do not have the elements that react with HCl
Felsic
Igneous
light in color (light minerals)
rich in Ca
reacts with acid
Mafic
Igneous
dark in color (dark minerals)
rich in Fe + Mg
don’t react with acid
Banding
Layers have been formed by minerals being stacked ontop of each other under immense pressure and heat. Banding can be caused by differing minerals or grain size
