More ideas from wilson
Convection currents in the mantle cause oceanic plates to spread apart as new rock rises to the surface at spreading zones.

Convection currents in the mantle cause oceanic plates to spread apart as new rock rises to the surface at spreading zones.

kimberlite with diamond

This is rock with diamonds growing out of it. This rock comes from the Finsch Diamond Mine in South Africa. Discovered in 1961 produces over 2 million diamond yearly.

Basalt

Basalt is a fine-grained, dark-colored extrusive igneous rock composed mainly of plagioclase and pyroxene. The specimen shown is about two inches (five centimeters) across.

Obsidian

Obsidian is a dark-colored volcanic glass that forms from the very rapid cooling of molten rock material. It cools so rapidly that crystals do not form. The specimen shown above is about two inches (five centimeters) across.

Granite

Granite is a coarse-grained, light colored, intrusive igneous rock that contains mainly quartz and feldspar minerals. The specimen above is about two inches (five centimeters) across.

Basalt

Basalt is a fine-grained, dark-colored extrusive igneous rock composed mainly of plagioclase and pyroxene. The specimen shown is about two inches (five centimeters) across.