Amakinite

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Amakinite is a semi-transparent mineral in the brucite group with the formula (Fe2+, Mg)(OH)2. It has a pale green to yellow-green color and quickly turns brown in air due to the formation of Fe(OH)3. It ranks 3.5–4 on the Mohs hardness scale and has a specific gravity around 2.93. Optically, it is uniaxial. Cleavage is poor or indistinct, and its fracture is irregular to uneven.

Amakinite typically forms as splotchy, anhedral crystals within other rocks, often kimberlite, the diamond-bearing rock. It is slightly magnetic. The mineral was discovered in 1962 and is named after the Amakin Expedition, which prospected diamond deposits in Yakutia, in the Russian Far East. Its IMA symbol is Amk, and it belongs to the trigonal crystal system.