Images
Formula: Mg3(BO3)2
Anhydrous borate
Specific gravity: 3.10
Hardness: 6½
Streak: White
Colour: Colourless; colourless in transmitted light
Solubility: Readily soluble in warm hydrochloric or sulphuric acid
Melting Point = ~ 1340oC
Environments
Kotoite is an uncommon mineral typically formed in the contact zone of
magnesium-rich skarn borate deposits
(HOM).
Localities
At the Neichi mine, Japan, kotoite is associated with ludwigite,
suanite, szaibélyite and
warwickite
(HOM).
At the type locality, the North orebody, Hol Kol Mine, Suan-gun, North Hwanghae Province, North Korea, kotoite is found in
the contact metamorphic zone of a granitic
intrusion into dolostone, associated with
fosterite, norbergite,
spinel, ludwigite,
szaibélyite, fluoborite,
clinohumite and dolomite
(AM 24.406, HOM, Mindat).
Kotoite alters to szaibélyite under hydrothermal conditions
(Dana).
Back to Minerals