NHSV Geology: Rocks

basalt

Igneous. Dark, pretty even grain. Volcanic, low silicate

granite

Igneous. all sorts of colors. made from mica, feldspar, quartz. Bigger variation/speckled. Plutonic

gabbro

Igneous. pretty dark, some texture. Plutonic, flows fast.

andesite

lighter rock, higher silicate, volcanic

obsidian

igneous, glass

sandstone

sedimentary. highly variable, sandy

limestone

sedimentary. very similar to sandstone

shale

sedimentary. Similar to slate. Mud particles, layering effect that can peel

coal, bituminous

sedimentary. dark, looks like coal

breccia

conglomerate, sharp edges, chunks of rock

chert

sedimentary. type of limestone

quartzite

metamorphic, more polished

gneiss

metamorphic, foliations, tightly compact

schist

metamorphic, some foliations, shiny

slate

metamorphic, shale but harder

marble

metamorphic, compact limestone, polished

coal, anthracite

metamorphic, higher grade coal, packed tighter, higher % C