Abstract

Keilite, (Fe,Mn,Mg,Ca,Cr)S, from the Zakłodzie enstatite achondrite is described. Forming xenomorphic grains up to 0.5 mm in diameter, the keilite is associated with troilite (or pyrrhotite), Fe-Ni metal, an (Fe,Zn,Mn)S phase, enstatite (with relict forsterite in cores), plagioclase and accessory schreibersite, oldhamite, graphite, sinoite, and an SiO2 polymorph. It is brittle and possesses a good cleavage similar to that of galena, parallel to (001), (010), and (100). X-ray diffraction structural data reveal the following: cubic space group Fm3m, α = β = γ = 90°, a = 5.1717 (18) Å, unit-cell volume V = 138.32 (8) Å3; D = 3.958 g/cm3; Z = 4. The chemical formula based on 63 electron microprobe point analyses is: (Fe0.437, Mn0.356, Mg0.160, Ca0.017, Cr0.019, Zn0.001)S1.008. Compared with previously described keilites from enstatite chondrites, the Zakłodzie keilite is richer in (Mn,Ca,Cr)S and poorer in the Fe- and Mg-end-members and, consequently, it is nearer to alabandite and oldhamite. This is the first detailed description of keilite from a meteorite that is not an enstatite chondrite.

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