> Rocks & Soil

More on Igneous Rocks Sediment and Soil More on Sedimentary Rocks Thin Sections More on Metamorphic Rocks Petrology and Geochemistry Start Rock Collecting

What Is a Rock?
Everyone knows what a rock is, until you ask what it is exactly.

About Igneous Rocks
An introduction to the first great class of rock types.

About Sedimentary Rocks
An introduction to the second great class of rock types.

About Metamorphic Rocks
An introduction to the third great class of rock types.

Quick Rock Identification Tables
These tables will help you identify almost all the rock types you're likely to find--38 different ones.

Rock Pictures
Pictures of more than 50 different rock types.

Rock-Forming Mineral Formulas
Formulas of the 11 most common minerals, which make up the great majority of the world's rocks.

Geo-Quiz 4: Rocks
Bang your head on these 12 challenging quiz questions. Or use your rock hammer.

Common Rock Densities
A table of specific gravities for crustal modeling and engineering uses.

Artificial Rocks
Bricks, mortar, concrete, plaster and other artificial rocks.

Fulgurite Pictures
Selected photos of these bits of "fossil lightning."