Gemmology
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Monday, 27 January 2020


Gemmology — gemstones — characteristics, classification, specimens, library
Chromian diopside

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

Sanidine

— Most common in felsic volcanic rocks; in volcanic glass; also from mafic, high-temperature contact metamorphic, and hydrothermally altered rocks; from eclogite nodules in kimberlite (Anthony et al., 2001—2005).
Sanidine

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
Axinite-(Fe) — specimen 0400

Some exceptional specimens of gemstones from our ‘Repository’

More specimens of gemstones
Malaia garnet — specimen 0269
Colour change garnet — specimen 0272
Pargasite — specimen 0275
Ruby — specimen 0276

— 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

microcline — species of mineral; see microcline in ‘Classification’
milky quartz — variety of quartz; see milky quartz in ‘Classification’
mogánite — species of mineral; constituent of chalcedony
montebrasite — species of mineral; see montebrasite in ‘Classification’
Publications

Iverson, J., 2012 — Rare stones used in jewelry: smithsonite, cobaltite, pyrrhotite, nickeline, and Nuummite — Reports faceted specimens of smithsonite, cobaltite, pyrrhotite, nickeline, nuummite, shown by Mauro Pantò at the Tucson gem show (2012).
Anthony, J. W., Bideaux, R. A., Bladh, K. W., Nichols, M. C. (Eds), 2001—2005 — Cobaltite — Features the data of cobaltite; from ‘Handbook of Mineralogy’.