First report of domeykite and koutekite (copper arsenides) in siwalik sandstones of romehra, hamirpur district, Himachal pradesh

摘要

Koutekite and two polymorphs (i.e., alpha and beta) of domeykite (rare copper arsenide minerals) are reported for the first time from the uraniferous Lower Siwalik sandstones of the Romehra area, Hamirpur district, Himachal Pradesh. The calculated cell size of alpha-domeykite (Cubic) is a_0 = 9.646 A and that of beta-domeykite (Hexagonal) is a_0 = 7.151 A and c_0 = 7.304 A. Koutekite (Hexagonal) has measured cell parmeters of a_0 = 11.58 A and c_0 = 14.55 A. However, in koutekite of Romehra area an important interplanar spacing (d) at 2.081A is merging with 'd' of beta domeykite at 2.061A and another interplanar spacing at 2.47A exhibits comparatively higher intensity than the one published in JCPDS Data Card No. 13-581. Association of domeykite with uraniferous sandstones points out that uranium mineralisation in Lower Siwaliks of the Romehra took place possibly below 90 ℃ temperature.