Cobaltocalcite - Natural minerals and crystals

Cobaltocalcite, also known as cobaltoan calcite, is a variety of calcite whose crystal structure incorporates traces of cobalt substituting for calcium. This chemical peculiarity gives it its characteristic pink to raspberry-red colouring, sometimes reaching intense magenta hues. Crystallographically, it belongs to the rhombohedral system and has a hardness of 3 on the Mohs scale, typical of the carbonate group. This mineral generally forms in hydrothermal deposits associated with cobalt ores, notably in Morocco, the Democratic Republic of Congo and Italy, regions renowned for their gem-quality specimens. cobaltocalcite is formed through supergene alteration processes, whereby cobalt-rich solutions interact with pre-existing carbonate raw rocks and minerals">rocks. From an optical standpoint, cobaltocalcite displays high birefringence and characteristic effervescence on contact with dilute acids, a property common to all calcium carbonates. Its vitreous to pearly lustre and variable transparency, ranging from translucent to opaque, make it a particularly photogenic specimen for mineralogical collections.

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