Google - Research database allows searching of the scholarly literature.
USGS - Find information about mineral resources mined in your region. See how mining and extraction have changed over time in the United States and beyond, and how minerals are used today.
A comprehensive and in-depth database of minerals, including pictures, chemical formulas, animations of atomic structure, listings of physical and chemical properties of minerals, and links to other sites with mineral data.
Mineral Information Institute - A list of the most commonly used minerals, from aluminum to zirconium, including pictures.
Tulane - Stephan A. Nelson's introduction to minerals, written for an introduction to geology class.
An alphabetical glossary of relevant scientific terms.
A complete set of images that originally appeared as woodcuts in Agricola's 1550 classic book on mining.
Flash animation from W.W. Norton showing crystal growth.