Rocks The solid mineral material forming part of the surface of the earth and other planets.

Igneous Rocks “Fire Rocks”

Volcano Volcanoes may be active, dormant, or extinct.

Basalt Extrusive, dark, most common type of rock in the Earth’s crust, and makes up most of ocean floor.

Granite Intrusive (formed by slow cooling of magma underground). It is often used for building.

Obsidian Formed when lava cools quickly above ground. It is black glass with sharp edges and is used for making cutting tools and arrowheads.

Pumice Cooled quickly allowing air bubbles to form. Light enough to float on water.

Rhyolite

Scoria “Lava Rock”, lightweight extrusive rock with large, gas bubbles. It is usually red or dark in color.

Sedimentary Rocks “Layered rocks”

Breccia Made up of angular pieces cemented together by minerals.

Conglomorate Rounded pieces cemented together by minerals.

Limestone Made up from the mineral calcite which came from beds of evaporated seas and lakes and sea animal shells.

Sandstone Composed of sand-sized minerals or rock grains.

Shale A fine-grained rock made up of mud that is a mix of clay and salt minerals.

Travertine

Hematite

Coal The actual remains of dead plants from long ago.

Fossils

Metamorphic Rocks “Changed Rocks”

Gneiss Used to be granite, but heat and pressure turned it into gneiss. It as bands of gray and white.

Hornfel

Marble Used to be limestone until heat and pressure turned it into the metamorphic rock called marble.

Quartzite Was once sandstone and then heat and pressure transformed it into the metamorphic rock Quartzite.

Schist Used to be Basalt. Heat and pressure changed it into the Metamorphic rock, Schist.

Slate Used to be shale. Heat and pressure changed it into slate.

Metamorphic “Changed” Sandstone Quartzite Limestone Marble Granite Gneiss Basalt Schist Shale Slate