page_title: Hardystonite
hierarchical_section_title: Hardystonite
caption_attribution_description: English: Hardystonite, Clinohedrite, Calcite, Willemite Locality: Franklin Mine, Franklin, Franklin Mining District, Sussex County, New Jersey, USA (Locality at mindat.org) Size: 7.0 x 6.0 x 3.2 cm. A CLASSIC, multi-fluorescent specimen with 4 minerals from the famous Franklin Mine containing: BLUE hardystonite (ultra-rare Type Locality); ORANGE clinohedrite (ultra-rare Type Locality); RED calcite; and GREEN willemite from the Parker Shaft. This specimen is particularly rich in hardystonite. Ex George Elling Collection, a noted Franklin/Sterling Hill collector. Deutsch: Hardystonit, Klinoedrit, Calcit, Willemit Fundort: Franklin Mine, Franklin, Franklin Mining District, Sussex County, New Jersey, Vereinigte Staaten (Fundort bei mindat.org) Größe: 7.0 x 6.0 x 3.2 cm.
context_page_description: 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 it was not a useful ore mineral. Like many of the famous Franklin minerals, hardystonite responds to short wave ultraviolet light, emitting a fluorescence from dark purple to bright violet blue. In daylight, it is white to gray to light pink in color, sometimes with a vitreous or greasy luster. It is very rarely found as well formed crystals, and these are usually rectangular in appearance and rock-locked.
  Hardystonite has a chemical composition of Ca₂ZnSi₂O₇. It is frequently found with willemite, calcite, and clinohedrite. Hardystonite can be found altered to clinohedrite CaZn·H₂O through direct hydrothermal alteration.
  Other minerals often associated with hardystonite are franklinite, diopside, andradite garnet, and esperite.
  It was first described in 1899 by J.E. Wolff, when the New Jersey Zinc Company mines were located in what was called Franklin Furnace, in Hardyston Township, New Jersey.
context_section_description: 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 it was not a useful ore mineral. Like many of the famous Franklin minerals, hardystonite responds to short wave ultraviolet (254 nm wavelength) light, emitting a fluorescence from dark purple to bright violet blue.  In daylight, it is white to gray to light pink in color, sometimes with a vitreous or greasy luster.  It is very rarely found as well formed crystals, and these are usually rectangular in appearance and rock-locked.
   
  Hardystonite has a chemical composition of Ca₂ZnSi₂O₇. It is frequently found with willemite (fluoresces green), calcite (fluoresces red), and clinohedrite (fluoresces orange).  Hardystonite can be found altered to clinohedrite CaZn(SiO₄)·H₂O  through direct hydrothermal alteration.
  Other minerals often associated with hardystonite are franklinite, diopside, andradite garnet, and esperite (fluoresces yellow).
  It was first described in 1899 by J.E. Wolff, when the New Jersey Zinc Company mines were located in what was called Franklin Furnace, in Hardyston Township, New Jersey.
caption: Hardystonite in plain light, same sample as in fluorescent light image above right
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