Hardystonite
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Hardystonite is a rare calcium zinc silicate mineral first described from the Franklin, New Jersey, U.S. zinc deposits. It often contains lead, which was detrimental to the zinc smelting process, so i
Hardystonite is fluorescing blue in this Franklin Furnace specimen. Red is calcite, and green is willemite (size: 7.0 × 6.0 × 3.2 cm)
Hardystonite in plain light, same sample as in fluorescent light image above right
Franklin Furnace
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Franklin Furnace, also known as the Franklin Mine, is a famous mineral location for rare zinc, iron, and manganese minerals in old mines in Franklin, Sussex County, New Jersey, United States. This loc
Franklin Furnace ca. 1900
Fluorescent minerals of the Franklin mineral district: franklinite (black), willemite (green), and calcite (red). USGS