Petrology is the study of rocks, their composition, mineralogy, and origin. The detailed characteristics of chemistry, minerals, and mineral textures can lead to a detailed understanding of rock genesis. This information can then be used to address larger scale geologic issues, such as the tectonic development of mountain ranges and the eruptive history of volanoes.

Special documents


Using petrographic microscopes: adjustments and features

Internet resources

Exam study guides

Igneous rocks

Metamorphic rocks

Igneous rock labs White Mountain magma series

White Mountain magma series data set

White Mountain Magma Series discussions 1, 2, 3, 4

Photo gallery

New Hampshire magma series

New Hampshire magma series and Wooley Creek data sets

New Hampshire magma series and related discussions 1, 2, and 3

Photo gallery

Skaergaard and Stillwater intrusions

Skaergaard topics:1, 2, 3, 4

Stillwater topics: 1, 2, 3

Skaergaard-Stillwater photo gallery: 1; virtual field trips: 2, 3

Iceland lavas

Iceland lavas data set

Iceland geology and related descriptions: 1, 2, 3

Photo gallery

Metamorphic rock labs New England schists

New England geologic maps 1 and 2 and metamorphic maps 1 and 2

New England metamorphism discussions: 1

Photo gallery

New England mafic rocks

New England geologic maps 1 and 2 and metamorphic map 1

Metamorphism discussions focusing on mafic rocks: 1, 2, 3

Photo gallery

Norwegian eclogites

Geologic map of Fennoscandia, and very simplified map

Geologic discussions including the Norwegian Caledonides: 1 (short), 2 (pretty), 3 (field trip)

Photo gallery

Fault rocks

Fault rock discussions: 1, 2

Photo gallery

Forms and graph paper

Rock report form

Ternary graph paper, or maybe this green one is better with a color printer

Documents and spreadsheet utilities

Writing igneous rock hand sample descriptions

Writing metamorphic rock hand sample descriptions

Papers to replace field trips

Why petrology is so much fun

How to calculate norms from rock chemical analyses

NORM4 norm spreadsheet for single samples

NORM4 macro-enabled version for multiple samples

Estimating Fe3+ for amphiboles

Estimating Fe3+ in biotite

Making thin sections

Staining feldspars in thin section

Fill in missing values on REE diagrams!

Make ternary (triangle) diagrams in Excel!

Whole rock geochemical discriminant diagrams!

Image libraries

Igneous minerals in thin section: Common minerals in igneous rocks.

Igneous textures in thin section: Common textures in volcanic and plutonic rocks.

Metamorphic minerals in thin section: Common minerals in metamorphic rocks, excluding igneous minerals, above.

Metamorphic reactions in thin section: Mineral and texture evidence for reactions.

Metamorphic microstructures in thin section: Some common microstructures.

Moon rocks: Moon rocks and rock thin sections from NASA loaner sets.

Hand sketches in petrology, an almost forgotten art.

Petrology field trips

2000 trips

2001 trips

2002 trips

2003 trips

2004 trips

2006 trips

2009 trips

2011 trips

2013 trips

Other field trips here or here
SVG vector graphics files for figures I use in Petrology (native Inkscape)