MINERAL-E 

(Mn-Zn-arsenate)

Mineral-E, an unnamed chlorophoenicite-like mineral, occurs with secondary willemite from Franklin. The crystals are predominantly rectangular and elongate, but some are bladed. They are terminated by a rough pinacoid or a branching termination. This mineral is orthorhombic, Laue symmetry 2/m2/m2/m, with a = 21.80, b = 3.08, and c = 7.27 Å.

The color is dark brown, the luster is vitreous, cleavage was unobserved, and the density is 3.62 g/cm³. Optically, the crystals appear to be inhomogeneous and have an isotropic core, an inconsistent undulatory extinction, and a mean index of refraction of 1.76.

Chemically, it is a manganese zinc arsenate hydroxide hydrate containing FeO 0.3, MgO 2.4, CaO 0.5, ZnO 28.4, MnO 31.0, As₂O₅ 18.7, SiO₂ 1.1, with H₂O 17.6 by difference, total = 100.0 wt. %. The water value corrects an error in the original paper. The composition is consistent with it being a hydrated and oxidized chlorophoenicite, as discussed by Dunn et al. (1982b). Because there is some doubt about a clear 1:1 correlation of chemical and X-ray data and because of the anomalous optical data, it was decided not to name this mineral.

Copyright © 1995 by Pete J. Dunn			Website by Herb Yeates
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This page created: January 11, 2001