chapter 6 - rock identification study guide

gabbro

igneous, closely related to granite, dark in color, large reflective crystals, intrusive cooling

coal

sedimentary, can write with, glossy, black, burial, compaction

rock salt

sedimentary, halite, crystal form, semi translucent, evaporation

gypsum

sedimentary, light in color, white crusty powdery edges, chemical action

conglomerate

sedimentary, rounded fragments, cementation

coquina

sedimentary, shells stuck together, organic cementing

clay

sedimentary, beige/ crème, powder, weathering and erosion

scoria

igneous, dark in color, holey, extrusive cooling, mafic magma

basalt

igneous, dense, not shiny, black, little to no crystals, extrusive

diorite

igneous, intrusive cooling, large reflective black and white crystals

pumice

igneous, light in color, light density, holey, extrusive cooling, no crystals

tuff

igneous, powdery, white, flaky, buried as it cooled, compacted, extrusive cooling

rhyolite

igneous, salmon, few crystals, relative to granite, extrusive cooling, light in color

granite

igneous, speckled, light in color, large reflective crystals, intrusive cooling, cooks slowly

porphyry

igneous, the crystals shine, process was intrusive (crystals) and extrusively cooked, shiny white crystals, dull dark background

obsidian

igneous, volcanic glass, glassy, dark in color, instant cooling

sandstone

layering, rough/ gritty, cementation

slate

meta, foliated, low T, high P, red/ grey, smooth, semi shiny,

marble

meta, large crystals, white, low P, high T

gneiss

meta, light and dark stripes, foliated, crystals, high T, high P

quartzite

meta, salmon/ red spectrum, mostly red with some white, waxy, semi smooth, no foliation, low P, low T

schist

meta, shiny, large, reflective crystals, foliated, high T, high P

breccia

sedimentary, angular fragments

shale

solidified mud in rock form, layering/ layers, dark in color/ grey, smooth, cementation