Kobaltkromium

Kobaltkromium is a rare and naturally occurring mineral that belongs to the chromite group, with the chemical formula (Co,Cr)₂O₄, where cobalt (Co) and chromium (Cr) are the primary cations. It is a member of the spinel group of minerals, characterized by its cubic crystal structure and dark, metallic luster. Kobaltkromium typically forms as an accessory mineral in ultramafic and mafic igneous rocks, often associated with chromite, magnetite, and other spinel-group minerals.

The mineral was first described in the early 20th century, though it remains relatively uncommon compared to more widespread chromite or magnetite. Kobaltkromium is usually found in small, octahedral or dodecahedral crystals, often embedded within larger chromite grains. Its color ranges from dark brown to black, with a metallic to submetallic sheen. Due to its rarity and complex composition, kobaltkromium is primarily of academic interest rather than industrial significance.

Chemically, kobaltkromium is a mixed oxide, meaning it contains both cobalt and chromium in its crystal lattice. The substitution of cobalt for chromium in the spinel structure gives it distinct magnetic and physical properties compared to pure chromite. However, its occurrence is limited to specific geological settings, such as chromitite layers in ophiolitic sequences or certain types of layered intrusions.

While kobaltkromium is not widely exploited commercially, its study contributes to understanding the behavior of trace elements in igneous rocks and the formation of economically important chromite deposits. Collectors and mineralogists may seek out specimens due to its rarity and unique composition, though well-documented occurrences remain scarce.