21.40ct 22.5mm Hemimorphite blue round cabochon Super rare

Item Information

Dimensions (mm) 22.5 x 22.5 x 6.5mm
Weight (carats) 21.4 carats
Colors

ShangrilaGems

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We couldn’t believe our luck when we found this superb Hemimorphite. Bi-color Hemimorphite. It is untreated and the color is for real. It is truly neon, truly rare and awesome. Do not miss an opportunity to own this!

Hemimorphite is a rare gem quality form of zinc silicate. Hemimorphite is very closely associated with Smithsonite, another rare collector’s gem. For many years, hemimorphite and smithsonite were both classed together another gemstone called calamine because of the similarity. In 1803 it was discovered to be two different minerals by mineralogist, James Smithson (of the Smithsonian Institute). Hemimorphite is a zinc silicate, whilst smithsonite is a zinc carbonate; zinc silicate Hemimorphite is considered to be rarer than Smithsonite. . The name ‘hemimorphite’ originates from the Greek words ‘hemi’ and ‘morph’, which respectively translate as ‘half-shape’. The name refers to its unusual hemimorphic crystal form, which means that the axial ends of crystals are asymmetrical. One end of each crystal is rather blunt, dominated by a pedion (a single face), while the other is pointed and pyramidal. Hemimorphite can be identified by its distinct composition and unique crystal structure. Hemimorphite can be composed of over fifty percent zinc. Gemmologically, it has a refractive index of 1.614 to 1.636 and a density or specific gravity of 3.30 to 3.50. Its hardness is 5 on the Mohs scale. Few deposits of Hemimorphite yield gemstone quality materials. Some of the most significant deposits are from Vieille Montagne, Belgium and Aachen, Germany, Mexico, Russia (Siberia), The Congo, Namibia, Madagascar and the United States, including Pennsylvania, Montana, Colorado and New Mexico. Hemimorphite can occur in various tones of blue, green and colorless. Most gemstones are blue to blue-green, and look similar to chrysocolla or turquoise. The most desirable color is sky to Swiss blue, which is reminiscent of Paraiba tourmaline. Hemimorphite often exhibits bands of blue with white streaks, and it may also be found interspersed by a dark matrix. Gem quality hemimorphite typically ranges from transparent to translucent in clarity. There is no known treatment for this gemstone - it is natural and organic. Chemical Formula: Zn4Si2O7(OH)2•H2O - Hydrous basic zinc silicate Crystal Structure: Orthorhombic; tabular Color Blue green, colorless Hardness 5 on the Mohs scale Refractive Index: 1 614 to 1.636 Density 3 30 to 3.50 Cleavage Perfect Transparency Transparent to opaque Double Refraction +0.022 Luster Vitreous, adamantine Fluorescence: Weak

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Pricing & Details

Bid Increment $1.00
Starting Bid $750.00
Auction ID 555710
Watchers 5 watching
Viewed 317 times
Starts 19th Feb 2017 2:07pm PST
Ends 19th Feb 2017 3:10pm PST

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