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AUTUNITE

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Originally appearing in Volume V03, Page 49 of the 1911 Encyclopedia Britannica.
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AUTUNITE , or CALCO-URANITE, a See also:

mineral which is one of the " See also:uranium micas," differing from the more commonly occurring See also:torbernite (q.v.) or cupro-uranite in containing See also:calcium in See also:place of See also:copper. It is a hydrous uranium and calcium phosphate, Ca (UOz)z(PO4)z+8(or 12)See also:H2O. Though closely resembling the tetragonal torbernite in See also:form, it crystallizes in the orthorhombic See also:system and is optically biaxial. The crystals have the shape of thin plates with very nearly square outline (89° 17' instead of 90°). An important See also:character is the perfect micaceous cleavage parallel to the basal See also:plane, on which plane the lustre is pearly. The See also:colour is See also:sulphur-yellow, and this enables the mineral to be distinguished at a glance from the See also:emerald-See also:green torbernite. Hardness 2-21; specific gravity 3.05-3.19. Autunite is usually found with See also:pitchblende and other uranium minerals, or with ores of See also:silver, See also:tin and See also:iron; it sometimes coats See also:joint-planes in See also:gneiss and See also:pegmatite. Falkenstein in See also:Saxony, St Symphorien near See also:Autun (hence the name of the See also:species), and St See also:Day in See also:Cornwall are well-known localities for this mineral. (L. J.

End of Article: AUTUNITE

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