Dessauite-(Y)

Dessauite-(Y) is a mineral member of the crichtonite group with the formula (Sr,Pb)(Y,U)(Ti,Fe³⁺)₂₀O₃₈. It is associated with derbylite, hematite, rutile, karelianite, siderite, and calcite. Founded in the Buca della Vena Mine, Tuscany, Italy, the mineral was called dessauite in honor of professor Gabor Dessau (1907–1983).^[1]

Structure

Dessauite occurs as small, flattened rhombohedral crystals, tabular {001} with hexagonal outline. Members of the Crichtonite group may be confused with ilmenite or hematite.^[2] The difference between dessauite and other minerals in the crichonite group is the occurrence of three additional octahedral sites and of a site in square pyramidal coordination, all with low occupancies. The mineral is black and opaque, presents a metallic luster, and it is brittle. Dessauite presents dimensions of diameter up to 1mm and thickness up to 0.2mm. In reflected plane-polarized light the color is ash-grey with pale bluish tones.^[1] The calculated density is 4.68 g/cm³. The habit is tabular, forming thin dimensions in one direction and hardness of 6.5 and 7.^[3] Dessauite differs from other elements of the crichtonite group because of the quantity of cations and X-ray diffraction patter.

Occurrence

Dessauite was found in the Buca della Vena Mine, Apuan Alps, northern Tuscany, Italy, with many other minerals, coming from hydrothermal fluids circulating through a small hematite-barite ore deposit within dolomite, during an alpine metamorphic event. It occurs in calcite veins hosted within dolomite and is associated with calcite, rutile, hematite, siderite, and derbylite.^[1]

See also

• List of minerals

References