other names: Finder's Diamond, Topaz (enlg.)
mineral class: Island silicates with tetrahedral anions
chemical formula: Al2SiO4(F, OH)2
Chemical elements: Aluminum, silicon, oxygen, fluorine, hydrogen
Similar minerals: /
colour: u.a. white, blue, pink, yellow, brown
shine: Glass gloss
crystal structure: orthorhombic
mass density: 3,5
magnetism: not magnetic
Mohs hardness: 8
stroke color: White
General information about the Topas:
Of the topaz describes a mineral that belongs to the group of island silicates and that can appear in different colors but always has a white line color. With a Mohs hardness of 8, this fluorosilicate is one of the hard gemstones and is characterized by complete cleavage and mussel to uneven fracture. The area-rich and sometimes very large crystals can be of long prismatic or columnar form and white to a glassy gloss. The transparency of the topaz ranges from delicate translucent to completely transparent.
The topaz can crystallize in different colors, with colorless, pink, light blue, brown, yellow and orange specimens being most commonly found. Pale green topaz are extremely rare and therefore valuable. Topazes mainly consist of fluorine and have a proportion of hydroxide ions, which usually makes up a maximum of thirty percent. The ratio of fluorine and hydroxide ion has a significant impact on the optics, refractive index, and physical properties of the topaz.
The exact origin of the name could not be clearly documented until today. Conjectures suggest that Topaz was derived from the ancient name of the island "Topazos". On this island in the Red Sea, topaz was never promoted, but olivine, a light green, also coveted gemstone as mineral. The theory that the origin of the name goes back to the Sanskrit word "tapas" for "shine" or "fire" is also permissible. Topazes have the property to change their color by vapor deposition and irradiation with electron or gamma rays and are therefore often manipulated in the jewelry industry. This also creates color variants that do not occur in nature.
Origin, occurrence and localities:
Topazes are distributed worldwide and sometimes form huge crystals, which in exceptional cases can have lengths of up to one meter and a weight of up to two and a half tons. They form on a base of other crystals and can be formed in river sediments, gneisses or pegmatites. The largest specimens come from Brazil, but there are also significant deposits in Mozambique, Mexico, Afghanistan, Sri Lanka, Burma, Japan, large parts of the United States, Germany, Switzerland and Scandinavia.
History and use of Topaz:
The first evidence for the use of topaz as a gem comes from ancient Egypt and go back to the second millennium BC. However, scientists suspect that topaz was known to humans much earlier, as the mineral is often associated with tin, a metal that had been selectively mined and processed into copper-tin alloys as early as the Bronze Age.
Today, the topaz is considered a coveted gem, which despite its frequency, depending on its color and origin sometimes high prices and is used for the production of precious jewelry. In particular, the rather rare pale blue specimens, which are summarized under the name "noble topaz", as well as the orange-red "Imperial Topaz" are considered prestige objects. Manipulated stones that appear violet, bright pink or dark green, are processed by many renowned jewelery houses to extravagant creations.