Gemmology
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Tuesday, 27 June 2017


Gemmology — gemstones — characteristics, classification, specimens, library
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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 163 different kinds of natural gemstones (104 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 728 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 7 specimens of synthetic stones.

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Repository
Spessartine — specimen 0652

Some exceptional specimens of gemstones from our ‘Repository’

More specimens of gemstones
Carnelian — specimen 0010
Titanite — specimen 0016
Carnelian — specimen 0020
Carnelian — specimen 0021

— More from ‘Repository

Currently there are 279 bibliographical references and abstracts to publications with gemmological or mineralogical thematics in the ‘Library’. The section comprises also a glossary with 381 terms.
Library
Glossary

synthetic — not a natural gemstone; may be a product of hydrothermal synthesis
taaffeite — synonym of magnesiotaaffeite-2N’2S
table — wide flat facet in the middle of the crown of faceted stone
tactite — a contact metamorphosed carbonate rock
Publications

Saussure, H. B., 1792 — Analyse de la dolomie — Published in 1792 in ‘Observations sur la Physique, sur l’Histoire Naturelle et sur les Arts’; contains the original description of the mineral dolomite.
Anthony, J. W., Bideaux, R. A., Bladh, K. W., Nichols, M. C. (Eds), 2001—2005 — Painite — Features the data of painite; from ‘Handbook of Mineralogy’.