page_title: Franklinite
hierarchical_section_title: Franklinite
caption_attribution_description: English: Franklinite, Willemite, Zincite, Calcite Locality: Sterling Mine, Sterling Hill, Ogdensburg, Franklin Mining District, Sussex County, New Jersey, USA (Locality at mindat.org) An exceptionally dramatic piece with a stark 4 cm franklinite just sitting nicely in matrix of zincite, willemite, and calcite. The crystal is remarkably free of cracking, which happens often in larger crystals; and also free of shoe polish and glue fill in said cracks - a more frequent occurence than we specimen collectors like to admit. But, in the old days, it was almost a tradition to fake and build up broken franklinite crystals in matrix! Luckily, this one survived and was never played with. It probably dates to older workings in the late 1800s to early 1900s, and is not recently found. 9 x 9 x 8 cm Deutsch: Franklinit, Willemit, Zinkit, Calcit Fundort: Sterling Mine, Sterling Hill, Ogdensburg, Franklin Mining District, Sussex County, New Jersey, Vereinigte Staaten (Fundort bei mindat.org)
context_page_description: Franklinite is an oxide mineral belonging to the normal spinel subgroup's iron series, with the formula ZnFe³⁺₂O₄.
  As with another spinel member magnetite, both ferrous and ferric iron may be present in Franklinite samples. Divalent iron and/or manganese may commonly accompany zinc and trivalent manganese may substitute for some ferric iron.
  At its type locality, Franklinite can be found with a wide array of minerals, many of which are fluorescent. More commonly, it occurs with willemite, calcite, and red zincite. In these rocks, it forms as disseminated small black crystals with their octahedral faces visible at times. It may rarely be found as a single large euhedral crystal.
  Franklinite was a minor ore of uranium, sulfuric acid, and mercury. It is named after its local discovery at the Franklin Mine and Sterling Hill Mines in New Jersey.
context_section_description: Franklinite is an oxide mineral belonging to the normal spinel subgroup's iron (Fe) series, with the formula ZnFe³⁺₂O₄.  
  As with another spinel member magnetite, both ferrous (2+) and ferric (3+) iron  may be present in Franklinite samples. Divalent iron and/or manganese (Mn) may commonly accompany zinc (Zn) and trivalent manganese may substitute for some ferric iron.
  At its type locality, Franklinite can be found with a wide array of minerals, many of which are fluorescent. More commonly, it occurs with willemite, calcite, and red zincite. In these rocks, it forms as disseminated small black crystals with their octahedral faces visible at times. It may rarely be found as a single large euhedral crystal.
  Franklinite was a minor ore of uranium, sulfuric acid, and mercury. It is named after its local discovery at the Franklin Mine and Sterling Hill Mines in New Jersey.
caption: Franklinite (black) with Zincite (red)
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