Gemmology
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Monday, 2 August 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

Gadolinite-(Y)

— In granite and alkalic granite pegmatites (Anthony et al., 2001—2005). Faceted specimens are extremely rare.
Gadolinite-(Y)

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
Citrine — specimen 0241

Some exceptional specimens of gemstones from our ‘Repository’

More specimens of gemstones
Moonstone — specimen 0095
Moonstone — specimen 0096
Spessartine — specimen 0098
Moonstone — specimen 0099

— 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

rose quartz — variety of quartz; see rose quartz in ‘Classification’
round — a commonly used shape in faceting a gemstone
rubellite — variety of elbaite; see rubellite in ‘Classification’
ruby — variety of corundum; see ruby in ‘Classification’
Publications

Overton, T. W., 2011 — Chondrodite from Mahenge, Tanzania — At the Tucson gem show (2011), some samples of chondrodite that were found near Mahenge, Tanzania, were shown.