Geology Lab Exam 2

Rhyolite

Minerals: quartz, K-feldspar, and biotite

Extrusive

Felsic and fine

Basalt

Minerals: Ca-plagioclase, augite, and olivine

Extrusive

Mafic and fine

Rhyolite (tuff)

Minerals: quartz, feldspar, and biotite

Extrusive

Felsic and pyroclastic

Key traits to identify: less dense than limestone

Diorite

Minerals: quartz, K-feldspar, and biotite

Intrusive

Intermediate and coarse

Gabbro

Minerals: augite, olivine, and ca-plagioclase

Intrusive

Mafic and coarse

Obsidian

Minerals: none

Extrusive

Mafic and Glassy

Granite

Minerals: quartz, feldspar, and muscovite

Intrusive

Felsic and coarse

Key traits: has a pinkish color with it that diorite does not

Andesite

Minerals: quartz, plagioclase, k-feldspar, and biotite

Extrusive

Intermediate and porphyritic

Key traits: easily identifiable biotite and a green like color

Scoria

Minerals: none

Extrusive

Mafic and vesicular

Key traits: volcanic ash, less dense, and has pores

Conglomerate

Clastic and Detrital

Key features: has pebbles (can have quartz)

High energy

Upper river, alluvial plane, beach

Gypsum

Crystalline and Chemical

Key features: soft, generally white/gray

Low

Oolitic limestone

Crystalline and Bioclastic

Key features: will react to acid, sand size spheres, and concentric layers

Low

Shale/Claystone

Clastic and Detrital

Key features: fine, commonly laminated, darker color, and sheet fragments

Low

lake, flood plain, lagoon, deep ocean basin, and shallow sea

Sandstone

Clastic and Detrital

Key features: well sorted, can have quartz, and reddish color

High

sand dunes, lower river, beach, delta, and continental shelf

Coquina

Clastic and Bioclastic

Key features: rice krispy, shell fragments, and reacts to acid

Low

Coal

Crystalline and biochemical

Key features: low density, black, very shiny, and plant fossils

Low

Crystalline limestone

Crystalline and biochemical

Key features: reacts to acid, dark gray, and dense

Low

Glaciers

conglomerate and sandstone

River Channels

conglomerate and sandstone

Beach

sandstone

Flood Plains

shale/claystone

Reefs

limestone and coral fossils

Deep Ocean

limestone and mudstone

Deep Marines

limestone and mudstone

Lakes

shale, limestone, sandstone, and conglomerate

Sand Dunes

well-sorted sandstone

Mountain slope

pebble to boulder breccia

Swamp/Marsh

coal

Delta

sandstone, slitstone, coal, and mudstone