Category Phyllosilicate Crystal system Monoclinic | Strunz classification 9.ED.15 Space group Cm | |
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Formula
(repeating unit) (Zn,Al)3(Si,Al)2O5(OH)4 Crystal class Domatic (m)
(same H-M symbol) | ||
Fraipontite is a zinc aluminium silicate mineral with a formula of (Zn,Al)3(Si,Al)2O5(OH)4.
It is a member of the kaolinite-serpentine mineral group and occurs as an oxidation product of zinc deposits. It occurs with smithsonite, gebhardite, willemite, cerussite and sauconite.
It was first described in 1927 for an occurrence in Vieille Montagne, Verviers, Liège Province, Belgium. It was named for Julien Jean Joseph de Fraipont (1857–1910), and Charles de Fraipont, geologists of Liege, Belgium. In addition to the type locality in Belgium, it has been reported from Tsumeb, Namibia; Laurium, Greece; Swaledale, North Yorkshire, England; the Silver Bill mine, Cochise County, Arizona, the Blanchard Mine, Socorro County, New Mexico and the Mohawk mine, San Bernardino County, California in the US; and from the Ojuela mine, Mapimi, Durango, Mexico.
A synonym for fraipontite is zinalsite which was reported in 1956 for an occurrence in Kazakhstan.