Brezinaite, a new chromium sulphide, occurs in the metal matrix and contiguous to silicate inclusions in the Tucson iron meteorite. The following average composition of brezin-aitewas determined by the electron microprobe: Cr 48.3; Ee 3.9; V 1.61; Ti 0.96; Mn 0.86; Ni 0.08; S 45.0, sum 100.71 wt.%. The unit cell is monoclinic with a = 5.96 ± 0.01, b= 3.425 ± 0.005, and c = 11.27 ± 0.015 Å β = 91° 32′, V = 229.97 Å3. Calculated X-ray density is 4.12 g/cm3 (Z = 2).

Very low iron content of the silicates, presence of chromium sulphide, significant amounts of silicon in the nickel-iron, and the chalcophile behavior of vanadium indicate a very high degree of reduction in Tucson similar to enstatite chondrites and enstatite achondrites.

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