TORBERNITE MINERAL FACTS Nevada Turquoise gem stones
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Torbernite Mineral Facts:

Chemical Formula: Cu(UO2)2(PO4)2 - 8H2O
Hydrated phosphate of copper and uranium.

Colors: Black color with brownish tinge, black streak.
It is strongly pleochroic in green and blue.

Hardness: 2 to 2.5  

Density: 3.4 to 3.6

Cleavage: One perfect cleavage on 001

Crystallography: Tetragonal.
Torbernite occurs in small square tables, that may be very thin or moderately thick, and the crystals are extremely simple in form. It also occurs in foliated and micaceous masses.

Luster:. Subadamantine, pearly on cleavage planes; transparent to subtranslucent..

Composition, Structure and Associated Minerals:
Torbernite has a perfect clevage parallel to the basal plane, giving extremely thin lamellae, and in this respect resembling mica, whence the name uran-mica, by which the mineral is sometimes called. The laminae are brittle and not flexible, and in this respect they differ from the laminae of mica minerals. Like all uranium minerals, it is radioactive and emits small quantities of toxic radon gas, so reasonable precautions should be taken in handling and storing it.
Torbernite is isostructural with the related and more common calcium uranium phosphate mineral, autunite.

Identification and Diagnostics
The mineral is bright green in emerald, grass or apple shades, has a lighter green streak
. Torbernite gives reactions for Cu and P and yields water in the closed tube. The bead reactions for uranium are masked by those of copper. The mineral is soluble in HNO3. The mineral is easily recognized by its color and other physical properties.

Torbernite is occasionally found as a coating on the walls of crevices in rocks. It occurs in Cornwall, England; at Scheeberg, Germany; at Joachimsthal, in the Czech Republic, and at many other places where other uranium minerals exist. It is probably in all cases a secondary product of weathering. Containing 61.2 per cent uranium trioxide, it is a minor ore of uranium. Attractive coloration and crystallization make it desirable as a mineral collector specimen.

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Please note that the author, Chris Ralph, retains all copyrights to this entire document and it may not be reproduced, quoted or copied without permission.

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