Gemmology
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Tuesday, 20 April 2021


Gemmology — gemstones — characteristics, classification, specimens, library
Indicolite

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

Titanite

— Also known as sphene; a common accessory mineral in intermediate and felsic rocks, pegmatites, and alpine veins; in gneisses, schists, and some skarns (Anthony et al., 2001—2005).
Titanite

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
Rock crystal — specimen 0752

Some exceptional specimens of gemstones from our ‘Repository’

More specimens of gemstones
Moonstone — specimen 0131
Bytownite — specimen 0133
Indicolite — specimen 0134
Indicolite — specimen 0139

— 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

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’
leucite — species of mineral; see leucite in ‘Classification’
Publications

Anthony, J. W., Bideaux, R. A., Bladh, K. W., Nichols, M. C. (Eds), 2001—2005 — Topaz — Features the data of topaz; from ‘Handbook of Mineralogy’.
Delamétherie, J. C., 1798 — Sur une pierre de l’Andalousie — Published in 1798 in ‘Journal de Physique, de Chimie et d’Histoire Naturelle et des Arts’; contains the original description of the mineral andalusite.