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About Rocks & Rock Collecting

Rocks of all types: how they form, what they mean, how to identify them.
  1. More on Igneous Rocks (25)
  2. More on Sedimentary Rocks (28)
  3. More on Metamorphic Rocks (13)
  4. Start Rock Collecting (33)
  5. Thin Sections (14)
  6. Petrology and Geochemistry (14)

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

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

Rock Picture Index
Master guide to rock pictures and descriptions on this site.

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.

Igneous Rock Types
The major igneous rock types in annotated photos.

Sedimentary Rock Types
The major types of sedimentary rocks in annotated photos.

Metamorphic Rock Types
The major metamorphic rock types in annotated photos, from regional, contact and mechanical metamorphism.

Rock Cycle Diagram
My version of this classroom staple.

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

Official State Rocks of the United States
Twenty-five states honor various rocks as official emblems. Here are all 17 of them.

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.

Rock Identification Tables
Identify 43 of the most common rock types: igneous, sedimentary and metamorphic.

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

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