Gemmology
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Wednesday, 4 October 2023


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
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Cerussite

— Common in the oxidised zone of lead deposits, where it may constitute an important ore (Anthony et al., 2001—2005). Faceted specimens are very rare. The largest faceted stone is a 408 carat from Tsumeb, Namibia (Arem, 1987: 64).
Cerussite

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
Rose quartz — specimen 0699

Some exceptional specimens of gemstones from our ‘Repository’

More specimens of gemstones
Sapphire — specimen 0148
Bowenite — specimen 0152
Moonstone — specimen 0162
Moonstone — specimen 0163

— 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

hackmanite — variety of sodalite; see hackmanite in ‘Classification’
hambergite — species of mineral; see hambergite in ‘Classification’
haüyne — species of mineral; see haüyne in ‘Classification’
heart — rare shape in faceting a gemstone
Publications

Anthony, J. W., Bideaux, R. A., Bladh, K. W., Nichols, M. C. (Eds), 2001—2005 — Fluorapatite — Features the data of fluorapatite; from ‘Handbook of Mineralogy’.
Anthony, J. W., Bideaux, R. A., Bladh, K. W., Nichols, M. C. (Eds), 2001—2005 — Phosphophyllite — Features the data of phosphophyllite; from ‘Handbook of Mineralogy’.