Topaz is an accessory mineral to felsic igneous, sedimentary, and hydrothermally altered rocks.

Topaz is an accessory mineral to felsic igneous, sedimentary, and hydrothermally altered rocks.

The crystal structure of topaz alternates between sheets of (F, OH)₂O and O along (010) with Al³⁺occupying the octahedral sites and Si⁴⁺ in the tetrahedral sites.

Fluorine can be substituted by hydroxide in topaz by up to 30 mol.% in nature and hydroxide-dominating topaz can be made in laboratories but has not been found in nature.

On occasion, cavities can be found within topaz and they are filled with a liquid called brewsterlinite. Brewsterlinite was discovered by David Brewster upon heating a sample of topaz.

After heating, the topaz lost mass, and through examination Brewster concluded Topaz was formed in a wet environment creating these liquid-filled cavities. This liquid is a hydrocarbon with a refractive index of 1·13. Topaz's crystal habit takes many forms. It can display a range of slender and long crystals to bulky and short.

There can also be variation in the terminations displaying blunt, pyramidal, chisel, or wedge-shaped terminations. The perfect cleavage {001} in topaz breaks no Si-O bonds within its structure and only breaks Al-O and Al-F bonds.

This cleavage is diagnostic for this mineral. The 2V optical angle in topaz can range from 48° to 69.5°. Low fluorine content yields a smaller angle and high fluorine content yields a larger angle. Topaz in its natural state is colourless, often with a greyish cast. It also occurs as a golden brown to yellow colour which makes it sometimes confused with citrine, a less valuable gemstone.

The specific gravity of all shades of topaz, however, means that it is considerably heavier than citrine (about 25% per volume) and this difference in weight can be used to distinguish two stones of equal volume. Also, if the volume of a given stone can be determined, its weight if it were topaz can be established and then checked with a sensitive scale. Likewise, glass stones are also much lighter than equally sized topaz.

A variety of impurities and treatments may make topaz wine red, pale grey, reddish-orange, pale green, or pink (rare), and opaque to translucent/transparent. The pink and red varieties come from chromium replacing aluminium in its crystalline structure.

Imperial topaz is yellow, pink (rare, if natural), or pink-orange. Brazilian imperial topaz can often have a bright yellow to deep golden brown hue, sometimes even violet. Many brown or pale topazes are treated to make them bright yellow, gold, pink, or violet coloured. Some imperial topaz stones can fade from exposure to sunlight for an extended period of time. Naturally occurring blue topaz is quite rare. Typically, colourless, grey, or pale yellow and blue material is heat treated and irradiated to produce a more desired darker blue. Mystic topaz is a colourless topaz that has been artificially coated via a vapor deposition process giving it a rainbow effect on its surface.

Although very hard, topaz must be treated with greater care than some other minerals of similar hardness (such as corundum) because of a weakness of atomic bonding of the stone's molecules along one or another axial plane (whereas diamonds, for example, are composed of carbon atoms bonded to each other with equal strength along all of its planes). This gives topaz a tendency to break along such a cleavage plane if struck with sufficient force.

Topaz has a relatively low index of refraction for a gemstone, and so stones with large facets or tables do not sparkle as readily as stones cut from minerals with higher refractive indices, though quality colourless topaz sparkles and shows more "life" than similarly cut quartz. When given a typical "brilliant" cut, topaz may either show a sparkling table facet surrounded by dead-looking crown facets or a ring of sparkling crown facets with a dull well-like table. It also takes an exceptionally fine polish, and can sometimes be distinguished from citrine by its slippery feel alone (quartz cannot be polished to this level of smoothness).

Another method of distinguishing topaz from quartz is by placing the unset stone in a solution of bromoform or methylene iodide. Quartz will invariably float in these solutions, whereas topaz will sink.

Topaz is commonly associated with silicic igneous rocks of the granite and rhyolite type. It typically crystallises in granitic pegmatites or in vapour cavities in rhyolite lava flows including those at Topaz Mountain in western Utah and Chivinar in South America. It can be found with fluorite and cassiterite in various areas including the Ural and Ilmensky mountains of Russia, Afghanistan, Sri Lanka, the Czech Republic, Germany, Norway, Pakistan, Italy, Sweden, Japan, Brazil, Mexico; Flinders Island, Australia; Nigeria, Ukraine and the United States. Topaz was found around the time of the 1700s in a pegmatite formation within the central Urals Mountains in Russia.

Brazil is one of the largest producers of topaz, some clear topaz crystals from Brazilian pegmatites can reach boulder size and weigh hundreds of pounds. The Topaz of Aurangzeb, observed by Jean Baptiste Tavernier weighed 157.75 carats (31.550 g). The American Golden Topaz, a more recent gem, weighed 22,892.5 carats (4,578.50 g). Large, vivid blue topaz specimens from the St. Anns mine in Zimbabwe were found in the late 1980s. Colourless and light-blue varieties of topaz are found in Precambrian granite in Mason County, Texas within the Llano Uplift. There is no commercial mining of topaz in that area. It is possible to synthesise topaz.

Topaz is used as a gemstone in jewellery and other adornments.

Common topaz in its natural state is colourless, though trace element impurities can make it pale blue or golden brown to yellow-orange.

Topaz is often treated with heat or radiation to make it a deep blue, reddish-orange, pale green, pink, or purple.

Topaz is a nesosilicate mineral, and more specifically, an aluminosilicate mineral.It is one of the hardest naturally occurring minerals and has a relatively low index of refraction. It has the orthorhombic crystal system and a dipyramidial crystal class.

It occurs in many places in the world. Some of the most popular places where topaz is sourced are Brazil and Russia. Topaz is often mined in open pit or alluvial settings.

Ref: Wikipedia

Topaz promotes truth and forgiveness. It is known as the stone of success.

According to Metaphysical Healers Topaz releases one from tension and induces relaxation.

Topaz brings joy, generosity, abundance and good health. It has been used in healing wounds and skin disorders.

It can promote in one the individuality and creativity, while providing confidence in trusting ones decisions.

It aids problem-solving and assists in expressing ideas. Topaz promotes openness and honesty, self-realisation and self-control.