Jacobsite
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Physical & Optical Properties
Mohs Hardness
Crystal System
Value & Market
Where to Buy Jacobsite
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About Jacobsite
Jacobsite is a manganese iron oxide spinel mineral forming opaque to subtransparent black to brownish-black octahedral crystals with a submetallic to metallic luster. It occurs in metamorphic manganese ore deposits and is found in localities in Sweden (Jakobsberg, its namesake), Germany, South Africa, and Japan. Transparent gem-quality material is extremely rare, making faceted jacobsite a notable rarity among spinel-group mineral collectors.