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Friday, 22 January 2021

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 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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— Most common in felsic volcanic rocks; in volcanic glass; also from mafic, high-temperature contact metamorphic, and hydrothermally altered rocks; from eclogite nodules in kimberlite (Anthony et al., 2001—2005).

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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Rock crystal — specimen 0301

Some exceptional specimens of gemstones from our ‘Repository’

More specimens of gemstones
Bytownite — specimen 0133
Indicolite — specimen 0134
Indicolite — specimen 0139
Indicolite — specimen 0140

— 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.

hexagon — a shape in faceting a gemstone
hibonite — species of mineral; faceted specimens exist (Hainschwang, Notari, Massi, Armbruster, Rondeau, Fritsch, Nagashima, 2010)
hibschite — variety of grossular
howlite — species of mineral; see howlite in ‘Classification’

Freiesleben, J. C., 1836 — Calcit — Published in 1836 in ‘Magazin für die Oryktographie von Sachsen’; contains the original description of the mineral calcite.
Karsten, D. L. G., 1808 — Erd-und steinarten. Magnesit — Published in 1808 in ‘Mineralogische Tabellen’; contains the original description of the mineral magnesite.