Gemmology
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Tuesday, 2 March 2021


Gemmology — gemstones — characteristics, classification, specimens, library
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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

Sinhalite

— A rare accessory mineral formed in boron-rich skarns at the contact of limestones with granite or gneiss (Anthony et al., 2001—2005). Faceted specimens are relatively rare. The largest faceted stone is a 158 carat from Sri Lanka (Arem, 1987: 173).
Sinhalite

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
Achroite — specimen 0730

Some exceptional specimens of gemstones from our ‘Repository’

More specimens of gemstones
Dolomite — specimen 0165
Chrysoberyl — specimen 0166
Opal — specimen 0167
Johachidolite — specimen 0174

— 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

pargasite — species of mineral; see pargasite in ‘Classification’
pavilion — the bottom part of faceted stone
pear — a commonly used shape in faceting a gemstone
pectolite — species of mineral; see pectolite in ‘Classification’
Publications

Ludwig, C. F., 1804 — A. G. Werners Mineral — System vom Jahre 1803. Erste Klasse Erdige Fossilien. VI. Kalk — Geschlecht — Published in 1804 in ‘Handbuch der Mineralogie nach A. G. Werner’; contains the original description of the mineral anhydrite.
Jasche, C. F., 1817 — Das Rothmanganerz in der Gegend von Elbingerode am Harz — Published in 1817 in ‘Kleine Mineralogische Schriften’; contains the original description of the mineral rhodonite.