Gemmology
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Saturday, 7 December 2024


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

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

Cordierite

— In thermally metamorphosed argillaceous sediments and regionally metamorphosed schists, gneisses; in mafic igneous rocks and granites (Anthony et al., 2001—2005). The gemstone bears the name iolite.
Cordierite

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
Chrysoprase — specimen 0697

Some exceptional specimens of gemstones from our ‘Repository’

More specimens of gemstones
Brazilianite — specimen 0002
Hyacinth — specimen 0009
Carnelian — specimen 0010
Titanite — specimen 0016

— 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

dike — a sheet of rock that formed in a crack in a pre-existing rock body
diopside — species of mineral; see diopside in ‘Classification’
dodecagon — rare shape in faceting a gemstone
dolomite — species of mineral; see dolomite in ‘Classification’
Publications

Lorenzen, J., 1884 — Undersøgelse af Mineralier fra Grønland — Published in 1884 in ‘Meddelelser om Grønland’; contains the original description of the mineral kornerupine.
Anthony, J. W., Bideaux, R. A., Bladh, K. W., Nichols, M. C. (Eds), 2001—2005 — Chromdravite — Features the data of chromium-dravite; from ‘Handbook of Mineralogy’.