franklinite

mineral

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June 26, 2026

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Franklinite is an iron-black, slightly magnetic mineral with the chemical formula ZnFe₂O₄. It is an oxide of iron and zinc and is found in octahedral crystals or in massive form. Franklinite is part of the magnetite series of minerals. It is often found in association with zincite, a zinc oxide mineral that is typically blood-red, and white calcite. Notable occurrences of franklinite have been reported in Franklin and Sterling Hill, New Jersey.12

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magnetite
franklinite (zinc iron oxide, ZnFe₂O₄), jacobsite (manganese iron oxide, MnFe₂O₄), and trevorite (nickel iron oxide, NiFe₂O₄). All are magnetic, although franklinite and jacobsite are only weakly so; magnetite, which frequently has distinct north and south poles, has been known for this property since about 500…
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franklinite (zinc iron oxide, ZnFe₂O₄), jacobsite (manganese iron oxide, MnFe₂O₄), and trevorite (nickel iron oxide, NiFe₂O₄). All are magnetic, although franklinite and jacobsite are only weakly so; magnetite, which frequently has distinct north and south poles, has been known for this property since about 500…
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