COW SKULL INLAID TURQUOISE MOSAIC ART SOUTHWESTERN COOL
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Sold Date: 10/30/2010
Channel: Online Auction
Hello I am selling three different types of skulls that are hand made this week. I have the pleasure of listing this rare 19 X 18 inch cow skull hand inlaid with tourquiose creating this one of a kind work of art. This would look great on a million dollar home. This was made by a local indian artist and was a gift to me. I selling this to help my new store get established so that I can provide you with more wonderful items throughout the year, while helping the FFA, 4H Club and the environment by providing scholarships and monies to local children to help them provide America with Sustainable Farming practices that will benefit all of us for future generations. So bid from the heart and know that this conversation peice will provide beauty to your home while proving for our Future Farmers of America. PS. this is a one of a kind work of art. Please bid to win and know that each dollar goes to help the local children. Thank you. More information about this beautiful blue/green stone."Turquoise is an opaque, blue-to-green mineral that is a hydrous phosphate of copper and aluminium, with the chemical formula CuAl6(PO4)4(OH)8·4H2O. It is rare and valuable in finer grades and has been prized as a gem and ornamental stone for thousands of years owing to its unique hue. In recent times, turquoise, like most other opaque gems, has been devalued by the introduction of treatments, imitations, and synthetics onto the market. The substance has been known by many names but the word turquoise, which dates to the 17th century was derived from the French language turques, because it was first brought to Europe from Turkey from the mines in Persia. Pliny referred to the mineral as callais and the Aztecs knew it as chalchihuitl. Properties of turquoise Even the finest of turquoise is fracturable, reaching a maximum hardness of just under 6, or slightly more than window glass. Characteristically a cryptocrystalline mineral, turquoise almost never forms single crystals and all of its properties are highly variable. Its crystal system is proven to be triclinic via X-ray diffraction testing. With lower hardness comes lower specific gravity (2.60–2.90) and greater porosity: These properties are dependent on grain size. The lustre of turquoise is typically waxy to subvitreous, and transparency is usually opaque, but may be semitranslucent in thin sections. Colour is as variable as the mineral's other properties, ranging from white to a powder blue to a sky blue, and from a blue-green to a yellowish green. The blue is attributed to idiochromatic copper while the green may be the result of either iron impurities (replacing aluminium) or dehydration. The refractive index (as measured by sodium light, 589.3 nm) of turquoise is approximately 1.61 or 1.62; this is a mean value seen as a single reading on a gemmological refractometer, owing to the almost invariably polycrystalline nature of turquoise. A reading of 1.61–1.65 (birefringence 0.040, biaxial positive) has been taken from rare single crystals. An absorption spectrum may also be obtained with a hand-held spectroscope, revealing a line at 432 nanometres and a weak band at 460 nanometres (this is best seen with strong reflected light). Under longwave ultraviolet light, turquoise may occasionally fluoresce green, yellow or bright blue; it is inert under shortwave ultraviolet and X-rays. Turquoise is insoluble in all but heated hydrochloric acid. Its streak is a pale bluish white and its fracture is conchoidal, leaving a waxy lustre. Despite its low hardness relative to other gems, turquoise takes a good polish. Turquoise may also be peppered with flecks of pyrite or interspersed with dark, spidery limonite veining. Formation As a secondary mineral, turquoise apparently forms by the action of percolating acidic aqueous solutions during the weathering and oxidation of pre-existing minerals. For example, the copper may come from primary copper sulfides such as chalcopyrite or from the secondary carbonates m...
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