The crystal chemistry and crystal structure of kuksite, Pb3Zn3Te6+P2O14, and a note on the crystal structure of yafsoanite, (Ca,Pb)3Zn(TeO6)2

Abstract

New discoveries of kuksite, Pb_3Zn_3Te^(6+)P_2O_(14), from the Black Pine mine, Montana, and Blue Bell claims, California, have enabled a detailed crystal-chemical study of the mineral to be undertaken. Single-crystal X-ray structure refinements of the structure indicate that it is isostructural with dugganite, Pb_3Zn_3Te^(6+)As_2O_(14), and joëlbruggerite, Pb_3Zn_3(Sb^(5+),Te^(6+))As_2O_(13)(OH,O). Kuksite from the Black Pine mine crystallizes in space group P321, with unit-cell dimensions a = 8.392(1), c = 5.204(1) Å, V = 317.39(8) Å^3, and Z = 1 (R_1 = 2.91% for 588 reflections [F_o > 4σF] and 3.27% for all 624 reflections), while Blue Bell kuksite has the unit cell a = 8.3942(5), c = 5.1847(4) Å, and V = 316.38(4) Å^3 (R_1 = 3.33% for 443 reflections [F_o > 4σF] and 3.73% for all 483 reflections). Chemical analyses indicate that solid-solution series exist between kuksite, dugganite, and joëlbruggerite. Raman spectroscopic and powder X-ray diffraction data are also presented for samples from both occurrences. 
\nThe crystal structure of the chemically related species yafsoanite, (Ca,Pb)_3Te_2^(6+)Zn_3O_(12), from the type locality (Delbe orebody, Kuranakh Au Deposit, Aldan Shield, Saha Republic, Russia), has been refined to R_1 = 2.41% for 135 reflections [F_o > 4σF] and 3.68% for all 193 reflections. A garnet-type structure has been confirmed and significantly improves upon the results of an earlier structure determination. 
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