Manganosite

Manganosite is a rare manganese oxide mineral with the chemical formula MnO. It is a member of the cubic mineral group known as the halite group, sharing the same crystal structure as common salt. Manganosite typically occurs as small, euhedral crystals or granular masses. Its color can range from grayish-black to greenish-black, and it has a dull to greasy luster. It is relatively soft, with a Mohs hardness of 3.5 to 4.

This mineral is found in a variety of geological environments. It is commonly associated with metamorphic rocks, particularly those that have undergone contact metamorphism or regional metamorphism under low to moderate oxygen fugacity. Manganosite often forms in manganese-rich skarns and hydrothermal veins. It can also be found in some meteorites. Notable occurrences include Långban in Sweden, Franklin and Sterling Hill in New Jersey, USA, and various locations in Japan and Italy.

Manganosite's rarity and specific formation conditions make it of interest to mineralogists. Its presence can indicate particular geochemical environments during rock formation. While not a major ore of manganese, it is sometimes found in association with commercially valuable manganese deposits. Its delicate nature and susceptibility to oxidation in surface conditions contribute to its relative scarcity in weathered environments.