Taaffeite (; BeMgAl₄O₈) is a mineral, named after its discoverer

Richard Taaffe Edward Charles Richard (Graf von) Taaffe (1898–1967), known as Richard, was an Austrian-Irish gemmologist who found the first cut and polished taaffeite in November 1945. Biography Taaffe was born and grew up on the Bohemian estate of Ellisch ...

(1898–1967) who found the first sample, a cut and polished gem, in October 1945 in a jeweler's shop in

Dublin Dublin (; , or ) is the capital and largest city of Republic of Ireland, Ireland. On a bay at the mouth of the River Liffey, it is in the Provinces of Ireland, province of Leinster, bordered on the south by the Dublin Mountains, a part of th ...

, Ireland.Dept. Mineralogy, British Museum, June 7 195
Taaffeite, a new beryllium mineral, found as a cut gem-stone.
Retrieved February 2015 As such, it is the only gemstone to have been initially identified from a faceted stone. Most pieces of the gem, prior to Taaffe, had been misidentified as

spinel Spinel () is the magnesium/aluminium member of the larger spinel group of minerals. It has the formula in the cubic crystal system. Its name comes from the Latin word , which means ''spine'' in reference to its pointed crystals. Properties S ...

. For many years afterwards, it was known only in a few samples, and it is still one of the rarest gemstone minerals in the world. Since 2002, the

International Mineralogical Association Founded in 1958, the International Mineralogical Association (IMA) is an international group of 40 national societies. The goal is to promote the science of mineralogy and to standardize the nomenclature of the 5000 plus known mineral species. Th ...

-approved name for taaffeite as a mineral is magnesiotaaffeite-2N'2S.

Discovery

Taaffe bought a number of

precious stones A gemstone (also called a fine gem, jewel, precious stone, or semiprecious stone) is a piece of mineral crystal which, in cut and polished form, is used to make jewelry or other adornments. However, certain rocks (such as lapis lazuli, opal, a ...

from a jeweller in October 1945. Upon noticing inconsistencies between the taaffeite and spinels, Taaffe sent some examples to B. W. Anderson of the Laboratory of the

London Chamber of Commerce London Chamber of Commerce and Industry (LCCI) is London’s key hub for the business community, we support members’ businesses through a range of services, advocate on behalf of London’s business community in the most important forums of pol ...

for identification on 1 November 1945. When Anderson replied on 5 November 1945, he told Taaffe that they were unsure of whether it was a

or something new; he also offered to write it up in ''Gemologist''.

Properties

In 1951, chemical and X-ray analysis confirmed the principal constituents of taaffeite as

beryllium Beryllium is a chemical element with the symbol Be and atomic number 4. It is a steel-gray, strong, lightweight and brittle alkaline earth metal. It is a divalent element that occurs naturally only in combination with other elements to form mi ...

magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ta ...

and

aluminium Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. I ...

, making taaffeite the first mineral to contain both beryllium and magnesium as essential components. The confusion between spinel and taaffeite is understandable as certain structural features are identical in both. Anderson ''et al.'',Anderson, B.W., Payne, C.J., and Claringbull, G.F., (1951
Taaffeite, a new beryllium mineral, found as a cut gemstone
Mineralogical Magazine 29, pp. 765–772 classified taaffeite as an intermediate mineral between spinel and

chrysoberyl The mineral or gemstone chrysoberyl is an aluminate of beryllium with the formula Be Al2 O4. The name chrysoberyl is derived from the Greek words χρυσός ''chrysos'' and βήρυλλος ''beryllos'', meaning "a gold-white spar". Despite ...

. Unlike spinel, taaffeite displays the property of

double refraction Birefringence is the optical property of a material having a refractive index that depends on the polarization and propagation direction of light. These optically anisotropic materials are said to be birefringent (or birefractive). The birefring ...

that allows distinction between these two minerals.

Usage

Because of its rarity, taaffeite is used only as a gemstone.

Formation and occurrence

Taaffeite occurs in

carbonate rock Carbonate rocks are a class of sedimentary rocks composed primarily of carbonate minerals. The two major types are limestone, which is composed of calcite or aragonite (different crystal forms of CaCO3), and dolomite rock (also known as dolosto ...

s alongside

fluorite Fluorite (also called fluorspar) is the mineral form of calcium fluoride, CaF2. It belongs to the halide minerals. It crystallizes in isometric cubic habit, although octahedral and more complex isometric forms are not uncommon. The Mohs sca ...

mica Micas ( ) are a group of silicate minerals whose outstanding physical characteristic is that individual mica crystals can easily be split into extremely thin elastic plates. This characteristic is described as perfect basal cleavage. Mica is ...

, spinel and

tourmaline Tourmaline ( ) is a crystalline silicate mineral group in which boron is compounded with elements such as aluminium, iron, magnesium, sodium, lithium, or potassium. Tourmaline is a gemstone and can be found in a wide variety of colors. The ...

. This extremely rare mineral is increasingly found in alluvial deposits in Sri Lanka and southern Tanzania, as well as lower grade taaffeite in limestone sediments in China.

References

{{reflist, refs= Collings, Michael R (2009)
Gemlore: An Introduction to Precious and Semi-Precious Stones
(2nd Ed). p. 152. Wildside Press LLC. {{ISBN, 1-4344-5702-8 Papers and proceedings of the International Mineralogical Association. General meeting, Mineralogical Society of America, Volume 9
p. 502
/ref> Thomas, Arthur (2008
Gemstones: properties, identification and use
New Holland Publishers. p. 74. {{ISBN, 1-84537-602-1
Mindat
/ref> Read, Peter G. (2005)
Gemmology
Butterworth-Heinemann. p. 5. {{ISBN, 0-7506-6449-5. Institut mineralogii, geokhimii, i kristallokhimii redkikh ėlementov (1966). Geochemistry and mineralogy of rare elements and genetic types of their deposits, Volume 2. Institut mineralogii, geokhimii i kristallokhimii redkikh elementov. (English Version Publisher: Israel Program for Scientific Translations). pp. 77–79. Geological abstracts, Issues 1–7259 (1992). Elsevier/Geo Abstracts, p. 565 Gemstones Magnesium minerals Aluminium minerals Beryllium minerals Hexagonal minerals

Discovery

Properties

Usage

Formation and occurrence

See also

References