This site provides a detailed look at the crystal structure and compositional variations of amphiboles. Also discussed are ways to assess the quality of analyses from looking at the stoichiometry of mineral formulas, how to estimate ferric iron, and special considerations affecting formula recalculation. A 3-D model of the mineral's structure is also included. Full description.

This searchable database, maintained by the Russian Foundation of Basic Research, includes 4785 entries (2365 unique mineral names). Each mineral can be searched by name, specification, crystal chemical formula, or crystal structure characteristics. The crystal structure information includes mineral name, specification, crystal chemical formula, space group, unit cell parameters, coordinates, thermal ... Full description.

This site hosts a computer application for thermobarometry. The program calculates pressures and temperatures for garnet, cordierite, spinel, sillimanite/kyanite, quartz anhydrous or hydrous pelitic assemblages. The user enters cation values for each mineral, and the model generates pressure vs. temperature graphs or data tables of the calculated isopleths. The program is derived from the shareware ... Full description.

This site provides an illustrated lecture about ocean chemistry from a geochemistry course offered by Dr. Scott Wood at the University of Idaho. Topics include geochemical processes that occur in estuaries, halmyrolysis, the concept of residence time for elements in the ocean, the mechanisms by which elements are added to or removed from seawater, carbonate behavior in seawater and a definition of ... Full description.

WEB-PHREEQ is a web-based computer application for aqueous geochemical modeling. WEB-PHREEQ was developed for classroom teaching and for routine calculation of the distribution of chemical species in water. Users can calculate the effects of mixing of waters, adding phases to the solution, or changing the solution's temperature, Eh, or pH. The site features an easy to use interface, frequently asked ... Full description.

This site examines the crystal chemistry of some common mineral groups, including garnet, plagioclase, pyroxene, mica (muscovite and biotite), and amphibole. For each group, the topics considered include: the sites in the crystal structure on which the principal substitutions take place, the typical ranges of observed composition variation, how to assess the quality of analyses from looking at the ... Full description.

This site consists of a compilation of crystallographic and physical property data for most of the rock-forming minerals. Thirteen mineral groups are included: single oxides, multiple oxides, hydroxides, sulfates, phosphates, orthosilicates (neosilicates), sorosilicates and cyclosilicates, chain silicates (inosilicates), sheet silicates (phyllosilicates), framework silicates (tektosilicates), high ... Full description.

The International Union of Crystallography maintains this clearinghouse of educational resources. There are many topics incorporated into this site, including applied crystallography, crystal growth, crystal structure analysis, crystals and their structures, diffraction, distance teaching, mathematical techniques, on-line courses, powder diffraction, and symmetry. This site would be useful for anyone ... Full description.

This site is a lecture from Tulane University that explores the symmetry observed in crystals. Topics covered include crystallographic axes, the crystal lattice, and unit cells. Tables and illustrations accompany the text. Full description.

This clearinghouse consists of crystallographic web sites. Topics include x-ray diffraction systems, sources & detectors, x-ray data, university crystallography laboratories, synchrotron, crystallographic tutorials, crystallographic software documentation (on-line), crystallographic software, crystallographic servers, crystallographic instrument accessories, crystallographic databases, crystallographic ... Full description.