Province of British Columbia
B.c. Ministry of Energy and Mines: Common Rock Forming Minerals
There are six common minerals most often found in rocks. They are quartz, feldspar, olivine, mica, pyroxene, and amphibole. This website provides photos and information on each, and discusses their importance when identifying rocks.
Other
Geologynet: Rock Forming Minerals
Use the search to find information on rock forming minerals. Characteristics including formula, color, cleavage, and hardness are presented in an easy-to-read chart.
University of Oregon
Ask Geo Man: Igneous Rock Forming Minerals
Ask GeoMan lists Olivine, Pyroxene, Amphibole, Feldspar, Mica and Quartz, as five common rock forming minerals. Characteristics of each are also given.