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Friday, 25 May 2018

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 172 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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— Primarily in cavities in basalts; in gneisses and amphibolites, and in dikes derived from syenitic magmas (Anthony et al., 2001—2005). Extreme rarity as faceted specimens.

The section ‘Repository’ contains data and photos of 745 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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Smoky quartz — specimen 0204

Some exceptional specimens of gemstones from our ‘Repository’

More specimens of gemstones
Variscite — specimen 0076
Variscite — specimen 0077
Rose quartz — specimen 0079
Petschite — specimen 0081

— 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 392 terms.

aquamarine — variety of beryl; see aquamarine in ‘Classification’
aragonite — species of mineral; see aragonite in ‘Classification’
arfvedsonite — species of mineral; faceted specimens exist
argillite — a fine-grained sedimentary rock composed predominantly of indurated clay particles

Klaproth, M. H., 1806 — Chemische Untersuchung des Datoliths — Published in 1806 in ‘Neues allgemeines Journal der Chemie’; contains the original description of the mineral datolite.
Anthony, J. W., Bideaux, R. A., Bladh, K. W., Nichols, M. C. (Eds), 2001—2005 — Gadolinite-(Y) — Features the data of gadolinite-(Y); from ‘Handbook of Mineralogy’.