Gemmology
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Tuesday, 28 June 2022


Gemmology — gemstones — characteristics, classification, specimens, library
Chromian diopside

GEMMOLOGY — GEMSTONES

characteristics, classification, specimens, library

As gemstones we accept cut specimens of crystals of natural mineral species having a visible transparency and certain durability. From over 4800 known minerals (according to data of the International Mineralogical Association), approximately 150 satisfy the above conditions and form crystals of sufficient size to be cut.

The section ‘Classification’ presents descriptions of 171 different kinds of natural gemstones (106 mineral species). The Nickel-Strunz systematic order (10th edition) is used. Since gemmology does not always follow the systematics of minerals in naming, many popular varieties or just ’names’ are listed.

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Classification
Featured

Epidote

— Characteristic of several facies of regionally metamorphosed rocks and some contaminated felsic igneous rocks; in contact zones between igneous and calcareous sedimentary rocks; from alteration of plagioclase (Anthony et al., 2001—2005). Faceted specimens are rare.
Epidote

The section ‘Repository’ contains data and photos of 760 specimens of gemstones. The smallest is just 1.96 mm (0.02 ct) ruby from Mozambique, and the largest — 70.11 mm (326.60 ct) rock crystal from Africa. Besides there are 8 specimens of synthetic stones.

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Repository
Opal — specimen 0716

Some exceptional specimens of gemstones from our ‘Repository’

More specimens of gemstones
Titanite — specimen 0016
Carnelian — specimen 0020
Carnelian — specimen 0021
Cordierite — specimen 0025

— More from ‘Repository

Currently there are 283 bibliographical references and abstracts to publications with gemmological or mineralogical thematics in the ‘Library’. The section comprises also a glossary with 391 terms.
Library
Glossary

albite — species of mineral; see albite in ‘Classification’
alexandrite — variety of chrysoberyl; see alexandrite in ‘Classification’
allanite-(Ce) — species of mineral; faceted specimens exist
almandine — species of mineral; see almandine in ‘Classification’
Publications

Anthony, J. W., Bideaux, R. A., Bladh, K. W., Nichols, M. C. (Eds), 2001—2005 — Afghanite — Features the data of afghanite; from ‘Handbook of Mineralogy’.
Anthony, J. W., Bideaux, R. A., Bladh, K. W., Nichols, M. C. (Eds), 2001—2005 — Sodalite — Features the data of sodalite; from ‘Handbook of Mineralogy’.