Gemmology
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Monday, 17 December 2018


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

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
Topaz — specimen 0560

Some exceptional specimens of gemstones from our ‘Repository’

More specimens of gemstones
Peridot — specimen 0312
Diamond — specimen 0315
Ruby — specimen 0318
Agate — specimen 0321

— 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

freibergite — species of mineral; faceted specimens exist
friedelite — species of mineral; see friedelite in ‘Classification’
fumarole — an opening in a Earth’s crust, often in the neighborhood of volcano, which emits steam and gases
gadolinite-(Y) — species of mineral; see gadolinite-(Y) in ‘Classification’
Publications

Anthony, J. W., Bideaux, R. A., Bladh, K. W., Nichols, M. C. (Eds), 2001—2005 — Chrysoberyl — Features the data of chrysoberyl; from ‘Handbook of Mineralogy’.
Anthony, J. W., Bideaux, R. A., Bladh, K. W., Nichols, M. C. (Eds), 2001—2005 — Magnetite — Features the data of magnetite; from ‘Handbook of Mineralogy’.