Dessauite-(Y) is a mineral member of the crichtonite group with the formula . It is associated with derbylite, hematite, rutile,

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siderite Siderite is a mineral composed of iron(II) carbonate (FeCO3). It takes its name from the Greek word σίδηρος ''sideros,'' "iron". It is a valuable iron mineral, since it is 48% iron and contains no sulfur or phosphorus. Zinc, magnesium and ...

, and

calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

. Founded in the Buca della Vena Mine, Tuscany, Italy, the mineral was called dessauite in honor of professor Gabor Dessau (1907–1983).

Structure

Dessauite occurs as small, flattened rhombohedral crystals, tabular with hexagonal outline. Members of the Crichtonite group may be confused with ilmenite or hematite. 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. 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. Dessauite differs from other elements of the crichtonite group because of the quantity of cations and X-ray diffraction pattern.

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.

References

{{Authority control Oxide minerals Natural materials Trigonal minerals Minerals in space group 148

Structure

Occurrence

See also

References