PONOMAREVITE, K4CU4OCL10, A NEW VOLCANIC SUBLIMATE MINERAL

Abstract

The new mineral was found in products of the Great Tolbachik fissure eruption, which occurred in Kamchatka in 1975 and 1976. During the eruption, this mineral was found as fine-grained brick-red incrustations on lava flows of the North and South breaches. In the posteruption stage, up to 1983, it was precipitated in sizable quantities not only as intergranular cement, but also as dark-red to black glassy crusts, 1 to 3 cm thick, in fractures between the first and second cinder cones. The same mineral also occurred in sizable quantities in fumarole incrustations of the second cinder cone. Ponomarevite in very thin chips is transparent and colored red, with a golden cast. The mineral is unstable; when exposed to the air for several days, its grains become opaque and change in color to grass green. The mineral is biaxial negative and nonpleochroic. Additional aspects of the subject, including chemical analyses, are reported.