Perlite - Pictures, links, and a brief description of the properties and applications of this siliceous rock.
Rakovan, John - Professor in the Department of Geology at Miami University, Oxford, OH. Includes information on Dr. Rakovan's research and teaching in mineralogy and geochemistry.
The Rock Gallery - Geological display of images and information including crystals, minerals and gems.
The Rock, Mineral, and Fossil Reference - Contains over 100 pictures of minerals, rocks and fossils, as well as information about classification, identification, the Science Olympiad Rocks and Minerals event and related topics.
Salt (MRBloch Archive) - A collection of material relating to salt [NaCl] and its influence on civilization. Includes sections on physiology, geology, archeology, palaeoclimatology, palaeogeography, production, religion, economics, and etymiology of salt.
YupRocks - high-resolution pictures of rocks and minerals, taken from personal collections, as well as the Calvin College Geology Department, Michigan, USA.