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New occurrences of duftite

Published online by Cambridge University Press:  14 March 2018

G. F. Claringbull*
Affiliation:
Department of Mineralogy, British Museum

Extract

During an examination of the mineral bayldonite, (Pb,Cu)7(AsO4)4(OH)2.H2O, for the purpose of obtaining standard X-ray powder data to compare with supposed single crystals of this species, it was found that a specimen purchased in 1948 as bayldonite from Ojuela mine, Mapimi, Durango, Mexico (B.M. 1948,267) gave a powder pattern related to those of members of the descloizite group and fairly close to but not identical with conichalcite, CuCaAsO4OH. It chanced that about the same time a specimen of a green botryoidal mineral from Brandy Gill, Caldbeek Fells, Cumberland, sent in by Mr. W. F. Davidson for determination was photographed and showed similar variations from the conichalcite pattern. Qualitative spectrographic comparison of the Mapimi and Brandy Gill materials with several conichalcites suggested that the differences in the powder photographs might be due to the presence of lead in the former.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1951

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References

1 O. Pufahl, Centralbl. Min., 1920, p. 295. [M.A. 1–150.]

1 Sandell, E. B., Colorimetric determinations of traces of metals. New York, 1944, p. 286.Google Scholar

2 Stolzite is new to this locality and good specimens were also exhibited at the meeting on November 2, 1950, by A. W. G. Kingsbury and J. Hartley.

1 Richmond, W. E., Amer. Min., 1940, vol. 25, pp. 441479. [M.A. 8–11.]Google Scholar