Cobaltoan Calcite with Heterogenite & Kolwezite

Description

Vivid magenta-pink Calcite crystals set against glossy black Heterogenite, with small green mineral accents across the natural matrix.

This striking cabinet specimen displays a dense covering of vivid magenta-pink Cobaltoan Calcite crystals across a pale natural matrix. Glossy black Heterogenite forms bold contrasting areas, while small green mineral spots, reported as Kolwezite, add further colour and mineralogical interest.

Kolwezi in the Katanga Copperbelt is known for colourful secondary cobalt and copper mineral assemblages. In Cobaltoan Calcite, cobalt within the calcite structure contributes to its characteristic pink colour. Here the bright crystal coating and dark associated mineral create a highly visual display from several angles.

Locality: Kolwezi Mining District, Lualaba Province, Democratic Republic of Congo. The associated green mineral is supplied as Kolwezite; that identification has not been independently analysed.

Condition and photography: Natural specimen, with no repairs or enhancements reported. Images were supplied on a dark background; colour can vary slightly with lighting and screen settings. Handle from the matrix and avoid acids or pressure on exposed Calcite crystals.

Calcite is calcium carbonate, a mineral with an unusually wide range of crystal forms. It occurs in sedimentary rocks, mineral veins and many other geological settings. Although the composition remains broadly the same, differences in growth conditions can produce dramatically different outlines, from broad faces to slender or densely grouped crystals. This variety is part of its interest for a mineral collection.

Calcite has well-developed cleavage: it can split along particular planes in its crystal structure. Its natural growth faces and cleavage surfaces therefore deserve careful distinction. Transparent, translucent and more opaque examples all occur. The shape, arrangement and surface character of this piece are more informative than colour alone, especially when comparing specimens from different localities.

The recorded origin is Kolwezi Mining District, Lualaba Province, DR Congo. Within a collection of Calcite specimens, this locality gives the piece a geographical identity alongside its particular crystal habit and natural setting.

The specimen measures 96 × 70 × 58 mm, with a recorded weight of 395 g. The proportions give a useful guide to its place in a display, with the individual crystal arrangement and mineral association remaining the principal points of interest.

Calcite is relatively soft and has pronounced cleavage, so support the stable part of the specimen when moving it. Avoid pressure on thin plates or projecting points. A secure display helps preserve the delicate edges and the arrangement of growth described for this piece.