Franklinite
Image: Robert M. Lavinsky (CC BY-SA 3.0)
Mineral NameFranklinite
Chemical Formula(Zn,Mn,Fe)Fe₂O₄
Mohs Hardness5.5
Crystal Systemcubic
Lustermetallic
Streak Colorreddish brown
Cleavagenone
Fractureconchoidal
Specific Gravity5.1
Colorsblack, dark brown
Transparencyopaque
Type LocalitySterling Hill, Ogdensburg, Franklin Mining District, Sussex County, New Jersey, USA
Mineral GroupOxides (Spinel Group)
Usescollector, minor ore of zinc and manganese
Associated Mineralszincite, willemite, calcite, rhodonite
Rarityuncommon
Description
This image displays black, submetallic to metallic Franklinite crystals, appearing somewhat blocky and granular, likely embedded within a lighter matrix.
Geological Context
Franklinite is a characteristic mineral of highly metamorphosed zinc-manganese ore deposits, famously found in the unique ore bodies of Franklin and Sterling Hill, New Jersey, where it forms under specific high-temperature, low-pressure conditions.
