Leiteite

leiteite

schneiderhohnite

tsumcorite

legrandite

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Formula: ZnAs3+2O4
Normal arsenite
Specific gravity: 4.31
Hardness: 1½ to 2
Streak: White
Colour: Colourless to brown
Environments

Hydrothermal environments

Leiteite is a rare arsenite that occurs almost exclusively at its type locality, the Tsumeb Mine, Oshikoto Region, Namibia. Other reported occurrences in Germany and Austria are in slag deposits, and are of anthropogenic origin (R&M 92.3.264-267).

At the type locality leiteite occurs with other zinc and arsenic-bearing minerals in an oxidised zone in a dolostone-hosted hydrothermal polymetallic ore deposit (HOM). Associated minerals include chalcocite, tennantite, reinerite, schneiderhöhnite, zincian stottite, zincroselite, tsumcorite, stranskiite, legrandite and smithsonite (HOM, AM 62.1259-1260).

Its association with the arsenite mineral schneiderhöhnite, which is considered to have formed at 40oC, would indicate a low temperature origin for leiteite (AM72.629-632). In arsenites arsenic occurs in its intermediate As(III) oxidation state, so it is likely that these levels had a reducing oxygen-deficient atmosphere during the crystallisation of these minerals (R&M 92.3.264).

In the type assemblage, leiteite is associated with smithsonite and schneiderhöhnite in chalcocite - tennantite ore (R&M 92.3.264).

Locations of further occurrences of leiteite at Tsumeb include:
The 29 and 30 levels, where leiteite was associated with legrandite, reinerite, stottite, stranskiite and zincroselite.
The third oxidation zone, mainly on the 44 and 45 levels, where leiteite was found in relatively large quantities. The first mineral to crystallise from the solution was leiteite, followed by reinerite, then legrandite, followed by adamite, then paradamite and lastly smithsonite.
In one pocket on the 44 level leiteite was associated with bunches of ludlockite needles. Another pocket on the 44 level contained the largest leiteite known. The assemblage of this pocket differed from the other finds and included adamite, köttigite and ianbruceite (R&M 92.3.264-267).

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