"Human Biology Lab Activities&amp"

Study the Formation of Different Igneous Rocks

Coarse-grained, with microcline, biotite and horblende phenocrysts.

Shiny black volcanic glass showing conchoidal fracture and some spherulites.

Glassy; most specimens float in water.

Grayish black trap rock.

Introduce your students to rocks formed from the cooling of magma and lava.

Pegmatite is igneous rock similar to granite but with larger crystals.

Obsidian is hard black colored, volcanic glass.