Hardystonite is a rare calcium zinc silicate mineral first described from the

Franklin, New Jersey Franklin is a borough in Sussex County, in the U.S. state of New Jersey. As of the 2010 United States Census, the borough's population was 5,045 U.S. The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...

zinc Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodi ...

deposits. It often contains

lead Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cu ...

, which was detrimental to the

zinc smelting Zinc smelting is the process of converting zinc concentrates ( ores that contain zinc) into pure zinc. Zinc smelting has historically been more difficult than the smelting of other metals, e.g. iron, because in contrast, zinc has a low boiling poin ...

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.Dunn, Pete J. Franklin and Sterling Hill, New Jersey: the world's most magnificent mineral deposits. Dr. Pete J. Dunn, 2004. Hardystonite-Clinohedrite-Calcite-170572

Hardystonite-Clinohedrite-Calcite-170572

Hardystonite has a chemical composition of Ca₂ZnSi₂O₇. It is frequently found with

willemite Willemite is a zinc silicate mineral () and a minor ore of zinc. It is highly fluorescent (green) under shortwave ultraviolet light. It occurs in a variety of colors in daylight, in fibrous masses and apple-green gemmy masses. Troostite is a vari ...

(fluoresces green), calcite (fluoresces red), and

clinohedrite Clinohedrite is a rare silicate mineral. Its chemical composition is a hydrous calcium-zinc silicate; CaZn(SiO4)·H2O. It crystallizes in the monoclinic system and typically occurs as veinlets and fracture coatings. It is commonly colorless, wh ...

(fluoresces orange). Hardystonite can be found altered to

CaZn(SiO₄)·H₂O through direct

hydrothermal alteration Metasomatism (from the Greek μετά ''metá'' "change" and σῶμα ''sôma'' "body") is the chemical alteration of a rock by hydrothermal and other fluids. It is the replacement of one rock by another of different mineralogical and chemical co ...

. Other minerals often associated with hardystonite are franklinite,

diopside Diopside is a monoclinic pyroxene mineral with composition . It forms complete solid solution series with hedenbergite () and augite, and partial solid solutions with orthopyroxene and pigeonite. It forms variably colored, but typically dull ...

, andradite garnet, and esperite (fluoresces yellow). It was first described in 1899 by J.E. Wolff, when the

New Jersey Zinc Company New is an adjective referring to something recently made, discovered, or created. New or NEW may refer to: Music * New, singer of K-pop group The Boyz Albums and EPs * ''New'' (album), by Paul McCartney, 2013 * ''New'' (EP), by Regurgitator, ...

mines were located in what was called

Franklin Furnace Franklin Furnace, also known as the Franklin Mine, is a famous mineral location for rare zinc, iron, manganese minerals in old mines in Franklin, New Jersey, United States. This locale produced more species of minerals (over 300) and more differ ...

, in Hardyston Township, New Jersey.

References

{{Commons category, Hardystonite, position=left Calcium minerals Sorosilicates Zinc minerals Tetragonal minerals Minerals in space group 113 Minerals described in 1899