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Zircon (from Persian: sarkun, golden) is a mineral belonging to the group of nesosilicates. Its chemical formula is Zr Si O4. The crystal structure of zircon is tetragonal (crystal class: 4/m 2/m 2/m). The natural color of zircon varies between colorless, yellow-golden, red, brown or green. Specimens that show gem quality are a popular substitute for diamond (but note that cubic zirconia is a completely different synthetic mineral with a different chemical composition).
Zircon is a remarkable mineral, if only for its almost ubiquitous presence in the crust of Earth. It is found in magmatic rock s (as primary crystallization products), in metamorphic rocks (as recrystallized grains) and in sedimentary rocks (as detrital grains). Large zircon crystals are seldom abundant. Their average size, e.g. in granite rocks, is about 100-300 µm, but they can also grow to sizes of several centimeters, especially in pegmatites.
The pervasive occurrence of zircon has become more important since the discovery of radiometric dating. Zircons contain amounts of uraniumUranium is a chemical element in the periodic table that has the symbol U and atomic number 92. A heavy, silvery-white, toxic, metallic , and naturally- radioactive element, uranium belongs to the actinide series and its isotope uranium-235 is used as the and thoriumThorium is a chemical element in the periodic table that has the symbol Th and atomic number 90. Notable characteristics Thorium is a naturally occurring, slightly radioactive metal. When pure, thorium is a silvery white metal that retains its lustre for (from 10 ppm up to 5 wt%) and can be dated using modern analytical techniques. Since zircons have the capability to survive geologic processes like erosionErosion is the displacement of solids ( soil, mud, rock, and so forth) by the agents of wind, water, ice, or movement in response to gravity. Although the processes may be simultaneous, erosion is to be distinguished from weathering, which is the decompos, transport, even high-grade metamorphismMetamorphism can be defined as the mineralogical, chemical and crystallographic changes in a solid-state rock, i. without melting, in response to new conditions of pressure and/or temperature, and/or introduction of fluids. Metamorphism produced with incr, they are used as protolith indicator s. The oldest minerals found so far are zircons from the Narryer Gneiss Terrane , Yilgarn Craton , Western AustraliaWestern Australia State flag ( In detail) Coat of Arms ( In detail) Capital Perth Governor HE Lieutenant General John Sanderson Premier Dr Geoff Gallop Area — Land — Marine — Total 2 529 875 km² 115 740 km² 2 645 615 km² Population Density 1 952 280 (2003, with an age of 4.404 billion years. This age is interpreted to be the age of crystallization. These zircons are not only the oldest minerals on earth, they also show another interesting feature. Their oxygen isotopic composition is interpreted by some to indicate that more than 4.4 billion years ago there was already water on the surface of the earth. This is a spectacular interpretation that has been published in top scientific journals but is widely disputed. It is most likely that the oxygen isotopes, and other compositional features (the rare-earth elements), simply record hydrothermal alteration. The timing of the alteration is uncertain, but this negates the necessity for ancient liquid-water oceans.
Owing to their uranium and thorium content, some zircons may undergo metamictizationMetamictization (sometimes called metamiction is a natural process resulting in the gradual and ultimately complete destruction of a mineral's crystal lattice, leaving the mineral amorphous. Affected material is therefore described as metamict . Certain m. This explains the highly variable properties of zircon.
Commercially, zircons are mined for the metal zirconium which is used for abrasive and isolating purposes. Bigger specimen are appreciated gemstones, owing to their high refraction (zicon has a refraction of around 1.95, diamond of around 2.4). The color of zircons that don't have gem quality can be changed by treating with heat. Depending on the amount of heat applied, colorless, blue and golden-yellow zircons can be made.
The name derives from the ArabicArabic is a Semitic language, fairly closely related to, for instance, the Hebrew language and the Aramaic language, spoken throughout the Arab world and widely known outside it. It has been a literary language for over 1500 years, and is the liturgical l word zarqun, meaning vermilionFor other meanings of the term, see Vermilion (disambiguation). Vermilion is a red pigment, chemically mercuric sulfide HgS or cinnabar, and the name of the typical color of the pigment, which is a bright but somewhat lighter and very slightly orange shad, or perhaps from the Persian zargun, meaning golden-colored. These words are corrupted into "jargoon", a term applied to light-colored zircons. Yellow zircon is called hyacinth, from a word of East Indian origin; in the Middle Ages all yellow stones of East Indian origin were called hyacinth but today this term is restricted to the yellow zircons.
Physical properties:
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