Affiliation:
1. V. S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, Koptyuga Pr. 3, Novosibirsk 630090, Russia
2. Institute of the Earth’s Crust, Siberian Branch of the Russian Academy of Sciences, Lermontova St. 138, Irkutsk 664033, Russia
Abstract
Potassium sulfide KFeS2 (hanswilkeite) has been identified in polymineralic inclusions in a diamond from the Udachnaya kimberlite pipe (Siberian craton, Yakutia). This is the second occurrence of hanswilkeite in nature and the first one in mantle-derived samples. Sulfide KFeS2 is monoclinic, the space group—C 2/c. Its crystal structure consists of chains with K in the interstices. The tetrahedra are centered by iron ions and linked by edges, thus forming chains of [FeS2] frameworks. The strongest lines of the electron diffraction powder pattern are 7.05 Å—(200); 5.34 Å (02¯0); and 3.05 Å (22¯0), and the angles between directions are <22¯0/02¯0>—60° and <22¯0/200>—30°. KFeS2 has been found as a discrete phase within polymineralic inclusions consisting of apatite, ilmenite, chondrodite, phlogopite, dolomite, and a fluid phase. The data obtained from the composition of the hanswilkeite (KFeS2) inclusion and other rare minerals (chondrodite, Mg-apatite, Cr-ilmenite) in primary inclusions in a diamond from the Udachnaya kimberlite testify to the important role of metasomatic processes in diamond formation.
Funder
Russian Science Foundation
IGM SB RAS
Subject
Geology,Geotechnical Engineering and Engineering Geology
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