Esperite is a rare complex calcium
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 ...
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 ...
silicate (PbCa
3Zn
4(SiO
4)
4) related to
beryllonite and
trimerite that used to be called ''calcium larsenite''.
Esperite has a white, greasy appearance in daylight and is much prized for its brilliant yellow green
fluorescence
Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore a lower photon energy, tha ...
under shortwave
ultraviolet
Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation ...
light. It is found in association with
calcite,
franklinite
Franklinite is an oxide mineral belonging to the normal spinel subgroup's iron (Fe) series, with the formula ZnFe3+2O4.
As with another spinel member magnetite, both ferrous (2+) and ferric (3+) iron may be present in Franklinite samples. Di ...
,
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 ...
,
hardystonite
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 t ...
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 ...
. It has also been found as prismatic crystals up to 1 mm in length at the
El Dragon Mine,
Potosi,
Bolivia in association with
allophane
Allophane is an amorphous to poorly crystalline hydrous aluminium silicate clay mineraloid. Its chemical formula is Al2O3·(SiO2)1.3-2·(2.5-3)H2O. Since it has short-range atomic order, it is a mineraloid, rather than a mineral, and can be ident ...
,
chalcomenite,
clinochalcomenite and
barite.
References
Mineral galleries*Pete Dunn, ''Franklin and Sterling Hill, New Jersey: the world's most magnificent mineral deposits'', part 3 p. 368 (1995)
*G. Grundmann, et al.: ''The El Dragon Mine, Potosi Bolivia'', Mineralogical Record v.21 #2 p. 142 (1990)
*Anthony et al., ''Handbook of Mineralogy'', Vol. 2 (silicates) part 1 p. 225 (1995)
Robbins, Manuel: Fluorescence Gems and Minerals under Ultraviolet Light Geoscience Press pp 50–51,243 (1994)
Calcium minerals
Lead minerals
Zinc minerals
Nesosilicates
Monoclinic minerals
Minerals in space group 11
Minerals described in 1928
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