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Monday, 25 September 2017

Gemmology — gemstones — characteristics, classification, specimens, library


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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— In gneisses, schists, included pegmatites, and quartz veins, from regional metamorphism of sedimentary rocks (Anthony et al., 2001—2005).

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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Carnelian — specimen 0471

Some exceptional specimens of gemstones from our ‘Repository’

More specimens of gemstones
Agate — specimen 0119
Colour change garnet — specimen 0120
Cordierite — specimen 0123
Agate — specimen 0124

— 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.

musgravite — synonym of magnesiotaaffeite-6N’3S
natrolite — species of mineral; see natrolite in ‘Classification’
nepheline — a rock-forming mineral, occurs in igneous rocks with low silica, and in their associated pegmatites
nephrite — a rock; see nephrite in ‘Classification’

Anthony, J. W., Bideaux, R. A., Bladh, K. W., Nichols, M. C. (Eds), 2001—2005 — Diaspore — Features the data of diaspore; from ‘Handbook of Mineralogy’.
Ludwig, C. F., 1803 — Rutil — Published in 1803 in ‘Handbuch der Mineralogie nach A. G. Werner’; contains the original description of the mineral rutile.