Calcite (w. malachite)

malachite

The broken (contact) surface of this specimen (hidden in Exhibit 1) reveals a concentrically banded knob of sparry white and pink (iron oxide stained) calcite. The outer layer, however, comprises coarse rhombohedral calcite crystals (to 30 mm on edge) with many of the faces frosted with a later crystallisation of sub-mm calcite rhombs. Finally, there is a sparse peppering of malachite as sub-spherical tufts and asymmetrically developed bow-ties (to 2 mm). The calcite superficially resembles material from the so-called "Ice Cream Pocket", but this is from a different (earlier) occurrence.
The specimen is from the collection of Clement Victor Latz, which was donated to the Australian Bureau of Mineral Resources (now Geoscience Australia) in 1976. There is no record of earlier provenance or location in the mine.