Abstract

Tivanite, V4.37Fe0.14Ti3.49O11.49(OH)4.51 (ideal VTiO3OH), is a new mineral species that has been found in the “green leader” gold lodes at Kalgoorlie, Western Australia. Is is monoclinic with space group P21/c, a = 7.494(5), b = 4.552(4), c = 10.005(8)Å, β = 129.79(2)°, Z = 1. The strongest powder diffraction lines (calculated) are 3.880(100)(111), 2.795(94)(211), 2.636(69)(113), 1.683(31)(224), 1.693(30)(122), 3.917(25)(011).

Tivanite occurs as minute multiply twinned crystals in quartz. Associated minerals are vandian muscovite and nolanite. Tivanite is black with a submetallic luster, lacks internal reflections, is moderately anisotropic, and has a specific gravity of 4.17 (calc.). Reflectivity values are 470 nm 16.8%, 546 nm 17.4%, 589 nm 17.7%. The microhardness is VHN 650 under a 50 g load.

The structure has been determined and refined to R = 0.12 using intensities collected for a multiply twinned crystal by the Weissenberg technique, using Cu radiation. The structure is based on an ordered occupation by V3+ and Ti4+ of half of the octahedral sites in a hexagonal closest-packed anion array. It can be described as an ordered 1:1 intergrowth of TiO2 with a rutile-type structure and VOOH with a diaspore-type structure.

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