Kolwesite

A copper-cobalt mineral named after Kolwezi

Kolwezite is a copper-cobalt hydroxycarbonate with the ideal formula CuCo(CO₃)(OH)₂. It forms in the oxidised zones of copper and cobalt deposits and belongs to the malachite-rosasite mineral group. Its name refers directly to Kolwezi, the mining district where its type locality is situated.

Kolwezite commonly occurs as spherical aggregates, small nodules or microcrystalline coatings. In the pieces shown here, its colour ranges from pale green to deeper green tones, with rounded or finely textured surfaces that stand out clearly against the matrix.

Green aggregates associated with drusy quartz

When examining kolwezite, useful details include the distribution and relief of the aggregates, the shade of green and the contrast with the quartz or surrounding rock. A piece may be visually appealing because of a few well-defined formations, a denser covering or the balance between the kolwezite and the sparkling microcrystals of its support.

Actual-item photos and videos show these differences from several angles, including the texture of the aggregates, the surface of the quartz and the overall presentation of each mineral.