Adamite

Adamite Locality: Ojuela Mine, Mapimí, Mun. de Mapimí, Durango, Mexico Dimensions: 14 cm x 9 cm x 3.3 cm Photo Copyright © Rob Lavinsky & irocks “iRocks.com”

Chemical Formula: Zn2(AsO4)(OH)
Locality: Chile, Atacama, Chañarcillo
Name Origin: Named after the French mineralogist Gilbert Joseph Adam (1795-1881).
Adamite is a zinc arsenate hydroxide mineral, Zn2(AsO4)(OH). It is a mineral that typically occurs in the oxidized or weathered zone above zinc ore occurrences. Pure adamite is colorless, but usually it possess yellow color due to Fe compounds admixture. Tints of green also occur and are connected with copper substitutions in the mineral structure. Olivenite is a copper arsenate that is isostructural with adamite and there is considerable substitution between zinc and copper resulting in an intermediate called cuproadamite. Zincolivenite is a recently discovered mineral being an intermediate mineral with formula CuZn(AsO4)(OH). Manganese, cobalt, and nickel also substitute in the structure. An analogous zinc phosphate, tarbuttite, is known.

Physical Properties

Cleavage: {101} Good, {010} Poor
Color:     Yellow, Green, Violet, Pink, Yellowish green.
Density: 4.3 – 4.5, Average = 4.4
Diaphaneity: Subtransparent
Fracture: Brittle – Generally displayed by glasses and most non-metallic minerals.
Hardness: 3.5 – Copper Penny
Luminescence: Fluorescent and phosphorescent, Short UV=yellow green, Long UV=yellow green.
Luster: Vitreous – Resinous
Streak: white

Photos:

This adamite sample is from Laurion, Attike, Greece. It is about 14 x14 cm.
This adamite sample is from Santa Eulalia, Chihuahua, Mexico. It is about 11 x 8 cm.
This adamite sample is from Ojuela mine, Mapimi, Durango, Mexico. It is about 28 x 21 cm.
 
This adamite sample is from Ojuela mine, Mapimi, Durango, Mexico. It is about 35 x 20 cm.
This adamite sample is from Ojuela mine, Mapimi, Durango, Mexico. It is about 4 x 10 cm.
Ojuela Mine, Mapimí, Mun. de Mapimí, Durango, Mexico © Steve Rust
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