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Monday, 20 August 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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— In granite and alkalic granite pegmatites (Anthony et al., 2001—2005). Faceted specimens are extremely rare.

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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Malaia garnet — specimen 0480

Some exceptional specimens of gemstones from our ‘Repository’

More specimens of gemstones
Malaia garnet — specimen 0230
Danburite — specimen 0234
Malaia garnet — specimen 0238
Malaia garnet — specimen 0239

— 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.

table — wide flat facet in the middle of the crown of faceted stone
tactite — a contact metamorphosed carbonate rock
tantalite-(Mn) — species of mineral; faceted specimens exist
tanzanite — variety of zoisite; see tanzanite in ‘Classification’

Rose, G., 1823 — Ueber den Feldspath, Albit, Labrador und Anorthit — Published in 1823 in ‘Annalen der Physik und der Physikalischen Chemie’; contains the original description of the mineral anorthite.
Shepard, C. U., 1839 — Notice of Danburite, a new Mineral Species — Published in 1839 in ‘American Journal of Science and Arts’; contains the original description of the mineral danburite.