Gemmology
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Saturday, 17 April 2021


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

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
Chalcedony — specimen 0694

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 391 terms.
Library
Glossary

hemimorphite — species of mineral; see hemimorphite in ‘Classification’
herderite — species of mineral; see herderite in ‘Classification’
hessonite — variety of grossular; see hessonite in ‘Classification’
hexagon — a shape in faceting a gemstone
Publications

Sundius, N., 1946 — The classification of the hornblendes and the solid solution relations in the amphibole group — Published in 1946 in ‘Sveriges Geologiska Undersökning’; contains the original description of the mineral ferro-actinolite.
Bruun-Neergard, T. C., 1807 — De la haüyne, nouvelle substance minérale — Published in 1807 in ‘Journal des Mines’; contains the original description of the mineral haüyne.