Cobaltoan Calcite Crystal Specimen

Description

A richly textured covering of pink Cobaltoan Calcite crystals with darker mineral areas, set against a pale natural matrix.

This 367 g Kolwezi cabinet specimen carries an extensive covering of rose-pink Cobaltoan Calcite. Numerous small crystal faces reflect the light across its uneven surface, with raised areas, shallow recesses and scattered darker mineral patches adding depth. A pale natural matrix is visible along the sides and back.

The darker associated mineral has not been confirmed by analysis, so it is described by its appearance. Cobaltoan Calcite owes its pink colouring to cobalt within the Calcite structure.

Locality: Kolwezi Mining District, Lualaba Province, Democratic Republic of the Congo.

Condition and photography: Natural contacts and surface irregularities are visible; inspect all views for detail. Colours can vary with lighting and screen settings. Handle from beneath the matrix and avoid acids.

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 110 × 70 × 50 mm, with a recorded weight of 367 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.