About Rocks & Rock Collecting

If you've never looked at a rock, here's what to do.

Everyone knows what a rock is, until you ask what it is exactly.

These tables will help you identify almost all the rock types you're likely to find--43 different ones.

Master guide to rock pictures and descriptions on this site.

Pictures of more than 50 different rock types.

An introduction to the first great class of rock types.

An introduction to the second great class of rock types.

An introduction to the third great class of rock types.

The major igneous rock types

The major types of sedimentary rocks.

The major metamorphic rock types, from regional, contact and mechanical metamorphism.

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

Twenty-five states honor various rocks as official emblems. Here are all 17 of them.

Bang your head on these 12 challenging quiz questions. Or use your rock hammer.

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

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

Selected photos of these bits of "fossil lightning."