Franklinite
Franklinite is named is named after its discovery locality, at Franklin and Sterling Hill, Sussex County, New Jersey, and ultimately for Benjamin Franklin, after whom the town of Franklin was named.
Franklinite forms iron-black, brown, red crystals with metallic lustre. Large crystals suitable for faceting are rare.
| General Information |
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| Chemical Formula | Anthony et al, Handbook of mineralogy (2001) |
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| Photos of natural/un-cut material from mindat.org |
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| Physical Properties of Franklinite |
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| Mohs Hardness | 6Anthony et al, Handbook of mineralogy (2001) |
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| Specific Gravity | 5.05 to 5.22Anthony et al, Handbook of mineralogy (2001) |
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| Tenacity | BrittleAnthony et al, Handbook of mineralogy (2001) |
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| Cleavage Quality | FairAnthony et al, Handbook of mineralogy (2001) |
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| Fracture | Uneven,Sub-ConchoidalAnthony et al, Handbook of mineralogy (2001) |
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| Optical Properties of Franklinite |
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| Optical Character | IsotropicAnthony et al, Handbook of mineralogy (2001) |
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| Colour |
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| Colour (General) | Iron-black, brown, red, may be tarnished; in reflected light, white to gray, with dark red internal reflectionsAnthony et al, Handbook of mineralogy (2001) |
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| Transparency | Translucent,OpaqueAnthony et al, Handbook of mineralogy (2001) |
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| Lustre | Dull (Earthy),Metallic,SubmetallicAnthony et al, Handbook of mineralogy (2001) |
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| Crystallography of Franklinite |
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| Crystal System | IsometricAnthony et al, Handbook of mineralogy (2001) |
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| Habit | Typically as octahedra, commonly with rounded edges, to 22 cm. Also exsolved within other minerals; coarse to fine granular, massive.Anthony et al, Handbook of mineralogy (2001) |
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| Geological Environment |
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| Where found: | In beds and veins formed by high temperature metamorphism of Fe, Zn, Mn rich marine carbonate sediments. As a minor mineral in some manganese and iron deposits.Anthony et al, Handbook of mineralogy (2001) |
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| Further Information |
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| Mineral information: | Franklinite information at mindat.org |
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| Significant Gem Localities |
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