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Kitagohaite, Pt7Cu, a new mineral from the Lubero region, North Kivu, democratic Republic of the Congo

par Cabral, Alexandre Raphael;Lehmann, Bernd;Skála, Roman;Kallistová, A.;Vymazalová, Anna;Sidorinová, Tamara;Jedwab, Jacques
Référence Mineralogical magazine, 78, 3, page (739-745)
Publication Publié, 2014

Article révisé par les pairs

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Résumé :

Kitagohaite, ideally Pt7Cu, is a new mineral from the Lubero region of North Kivu, emocratic Republic of the Congo. The mineral occurs as alluvial grains that were recovered together with other Pt-rich intermetallic compounds and Au. Kitagohaite is opaque, greyish white and malleable and has a metallic lustre and a grey streak. In reflected light, kitagohaite is white and isotropic. The crystal structure of kitagohaite is cubic, space group Fm3̄m, of the Ca7Ge type, with a = 7.7891(3) Å, V = 472.57(5) Å 3 and Z = 4. The strongest diffraction lines [d in Å (I)(hkl)] are: 2.246 (100)(222), 1.948(8)(004), 1.377 (77)(044), 1.174(27)(622), 1.123 (31)(444) and 0.893 (13)(662). The Vickers hardness is 217 kg mm-2 (VHN100), which is equivalent to a Mohs hardness of 31/2 and the calculated density is 19.958(2) g cm-3. Electron-microprobe analyses gave a mean value (n = 13) of 95.49 wt.% Pt and 4.78 wt.% Cu, which corresponds to Pt6.93Cu1.07 on the basis of eight atoms. The new mineral is named for the Kitagoha river, in the Lubero region. ©2014 The Mineralogical Society.