Legrandite

Legrandite Ojuela Mine, Mapimi, Durango, Mexico Miniature, 3.2 x 2.6 x 1.2 cm “Courtesy of Rob Lavinsky, The Arkenstone, www.iRocks.com”

Chemical Formula: Zn2(AsO4)(OH)·H2O
Locality: Ojuela mine near Mapimi, Durango.
Name Origin: Named after the Belgian mining engineer, Legrande.

Legrandite is a rare zinc arsenate mineral, Zn2(AsO4)(OH)·H2O.
It is an uncommon secondary mineral in the oxidized zone of arsenic bearing zinc deposits and occurs rarely in granite pegmatite. Associated minerals include: adamite, paradamite, kottigite, scorodite, smithsonite, leiteite, renierite, pharmacosiderite, aurichalcite, siderite, goethite and pyrite. It has been reported from Tsumeb, Namibia; the Ojuela mine in Durango, Mexico and at Sterling Hill, New Jersey, USA.

It was first described in 1934 for an occurrence in the Flor de Peña Mine, Nuevo Leon, Mexico and named after M. Legrand, a Belgian mining engineer .

History

Discovery date : 1932
Town of Origin : MINE FLOR DE PENA, LAMPAZOS, NUOVA LEON
Country of Origin : MEXIQUE

Optical properties

Optical and misc. Properties : Translucent
Refractive Index: from 1,67 to 1,74
Axial angle 2V: 50°

Physical Properties

Cleavage: {100} Imperfect
Color: Yellow, Yellowish orange.
Density: 4
Diaphaneity: Translucent
Fracture: Brittle – Conchoidal – Very brittle fracture producing small, conchoidal fragments.
Hardness: 4-5 – Fluorite-Apatite
Luster: Vitreous (Glassy)
Streak: white

Photos :

Legrandite Ojuela Mine, Mapimí, Mun. de Mapimí, Durango, Mexico Thumbnail, 2.8 x 0.6 x 0.3 cm “Courtesy of Rob Lavinsky, The Arkenstone, www.iRocks.com”
Legrandite Ojuela Mine, Mapimi, Mun. de Mapimi, Durango, Mexico Size: 2.0 x 1.3 x 1.3 cm (thumbnail) © danweinrich
Ojuela Mine, Mapimí, Mun. de Mapimí, Durango, Mexico © 2004 JBS
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