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Friday, 15 November 2019

Gemmology — gemstones — characteristics, classification, specimens, library
Smoky quartz


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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— The most abundant rare earth elements-bearing mineral, typically hydrothermal, although primary igneous occurrences are known; in granite and alkali syenites and pegmatites; in carbonatites (Anthony et al., 2001—2005). Faceted specimens are very rare.

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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Morganite — specimen 0422

Some exceptional specimens of gemstones from our ‘Repository’

More specimens of gemstones
Phenakite — specimen 0491
Phenakite — specimen 0493
Danburite — specimen 0501
Danburite — specimen 0502

— 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.

larimar — variety of pectolite; see larimar in ‘Classification’
lava — molten rock expelled by a volcano during an eruption
lazulite — species of mineral; see lazulite in ‘Classification’
lazurite — variety of haüyne; constituent of lapis lazuli; see lazurite in ‘Classification’

Anthony, J. W., Bideaux, R. A., Bladh, K. W., Nichols, M. C. (Eds), 2001—2005 — Uvite — Features the data of uvite; from ‘Handbook of Mineralogy’.
Haüy, R. J., 1792 — De l’Euclase — Published in 1792 in ‘Observations sur la Physique, sur l’Histoire Naturelle et sur les Arts’; contains the original description of the mineral euclase.