Vochtenite, a new mineral from the Basset Mine, southeast of Camborne in Cornwall, England, is a ferrous-ferric magnesium-bearing hydroxy uranyl phosphate mineral. It is monoclinic with a = 12.606, b = 19.990, c = 9.990 A, fl = 102.31 ~ Z = 3; the ideal formula is." (Fe z+,Mg)Fe3+[UOz/PO4]4(OH) 9 12-13 H20.The strongest lines in the X-ray powder diffraction pattern are: 9.998(100) (020) (344,471). Vochtenite is brown in colour with a bronzy lustre and is non-fluorescent. Mohs hardness is 2.5 and the density (calc.) = 3.663 g/cm 3. There is a prominent (010) cleavage. Vochtenite is optical biaxial negative, 2V (calc.) = 89(3)~ its dispersion is indiscernible. Refractive indices are a = 1.575(2),/3 = 1.589(2), y = 1.603(2), and the pleochroism is very weak. Orientation X(c011b is perpendicular to (010) and Z(y)/~ c is small. The mineral occurs as subparallel (0.5-1.0 mm) crystal aggregates with a pseudo-quadratic outline.

No abstract

No abstract

No abstract

No abstract