Topaz

by William Corry

Topaz is a silicate mineral that has been valued for centuries as a gemstone used in jewellery. Mineralogists call Topaz a hydroxy-fluoro-aluminum silicate, with the chemical formula Al2SiO4(F,OH)2. Topaz is the hardest silicate mineral, but it can be split with a single blow, a trait it shares with diamond. The crystals can reach an enormous size of several hundred pounds. Topaz make very attractive mineral specimens due to their high luster, lovely colours and well-formed, multi-faceted crystals. But most so-called topazes are really citrines, a Brazilian yellow quartz, produced by heating smoky quartz.

The name Topaz may come from the old Sanskrit word "tapaz," which means fire, based on a common misconception that all topaz is golden in colour. Pure Topaz is colourless, but it occurs in a variety of colours due to various impurities - yellow, brown, orange, beige, red and green. Some rare and exceptional topaz is pale pink, sherry red or blue. But most blue topaz is artificially created by irradiation of Pale Topaz from Brazil, Sri Lanka, Nigeria or China.

In ancient folklore, Topaz was believed to improve the eyesight of the wearer and to dispel enchantments. Topaz was also said to change colour in the presence of poisoned food or drink, which made it popular among early monarchs. It was believed that its mystical curative powers waxed and waned with the phases of the moon. Topaz was also said to cure insomnia and asthma as well as stop hemorrhaging. The Egyptians believed that Topaz was coloured with the golden glow of the sun god Ra, making it a powerful amulet to protect against harm. The Romans associated Topaz with Jupiter, also god of the sun in the Roman pantheon. The ancient Greeks said that it had the power to increase strength and make its wearer invisible in times of emergency. Some experts today maintain that the Topaz of modern mineralogists was unknown to the ancients, and that the stone called "topazos" was probably either chrysolite or peridot.

A famous Blue Topaz hunting ground is located in the Hill Country of Mason County, Texas, where North America's largest known gem-quality Topaz was discovered in 1904. This 1,296 gram, pale-blue crystal now resides in the Smithsonian Institution in Washington DC. Blue Topaz was designated the Texas state gem in 1969. Topaz is the birthstone for November while Blue Topaz is the birthstone for December.

Chemistry: Al2 SiO4 (F,OH)3
Crystal: Orthorhombic
SystemHardness: 8 (Mohs' scale)
Cleavage: Perfect in 1 direction, basal.
Fracture: Conchoidal
Specific Gravity:3.4 - 3.5+
Colour, Transparency & Luster