(Junoite and pekoite - first occurrences in the USSR.
These two Bi-Pb-Cu sulphides were found in the Bi mineralization of the Kochbulak deposit in eastern Uzbekistan, in which vein and pipe-like bodies of sulphide-quartz ore are enclosed in andesite-dacites. The junoite and pekoite typically occur together, in association with tetradymite, aikinite, gladite and sometimes cassiterite and Cu-Sn sulphides. Microprobe analyses are tabulated for 9 specimens; on a Cu2S-Bi2S3-Pb2S2 diagram, the analyses of junoite plot close to the theoretical composition (Cu2Pb3Bi8S16) whereas those for pekoite are scattered in the upper part of a line between the bismuthinite (Bi2S3) apex and gladite (CuPbBi5S9). The junoite XRD powder data can be indexed for a monoclinic cell, space group C2/m, with a 26.66, b 4.06, c 17.03 A, beta 127.20o; the patterns for pekoite are similar to those for the type material (M.A. 78-856) and give an orthorhombic cell with space group Pb21m.-R.A.H.