TORREYITE

(Mg,Mn)₉Zn₄(SO₄)₂(OH)₂₂.8H₂O 
Monoclinic, P2₁/c, a = 10.522, b = 9.433, c = 16.443 Å,
b = 94.91^o, Z = 4

Torreyite was first described from Sterling Hill as delta-mooreite by Bauer and Berman (1929b, 1929d); it has not been reported from Franklin. It was restudied and given its present name by

Prewitt-Hopkins (1949) who introduced incorrect X-ray data, which were corrected by Dunn et al. (1979a) in their description of the Mn-analogue of torreyite, lawsonbauerite. The unit-cell given above was refined from the powder X-ray data of Dunn et al. (1979a) by Dr. J. A. Mandarino (pers. comm.). The above formula was given by Treiman and Peacor (1982) by analogy with the subsequently determined structural formula of lawsonbauerite.

Description

Torreyite occurs as 1 mm blocky crystals, commonly in parallel growth and closely resembling the crystals of lawsonbauerite shown in figures 24-12 and 24-13. Torreyite also occurs as massive aggregates, some of which have a saccharoidal texture. Torreyite is light bluish-white or colorless, weakly translucent, with a luster varying from dull to vitreous and a density of 2.665 g/cm³. Cleavage was reported by Bauer and Berman (1929b) and stated to be on {010} by Prewitt-Hopkins (1949). It breaks easily into equant fragments. Twin lamellae are abundant and similar to those of plagioclase.

Optically, torreyite is biaxial, negative, 2V = 40^o, with a = 1.570, b = 1.584, and g   = 1.585. Although its description is incomplete, other aspects of its characterization can be inferred from the isostructural lawsonbauerite.      

Composition

Torreyite is a magnesium manganese zinc sulfate hydroxide hydrate mineral and the Mg-analogue of lawsonbauerite; Mn is present in substantial amounts. The only published data are those of Bauer and Berman (1929b) (Table 23).

Occurrence and paragenesis

Torreyite occured in an assemblage identical to those for lawsonbauerite. It occurs with rhodochrosite, zincite, and altered pyrochroite, which formed in a vein in calcite-franklinite-willemite  ore at Sterling Hill. Torreyite occurs in crevices in altered pyrochroite and is associated with, and may be younger than, mooreite.

Name

Torreyite was named in honor of Dr. John Torrey, an early American natural scientist with broad interests, who first published on local minerals in 1822.

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