Home > American Minerals V – October 1 > MS1655 Sincosite (Idaho!)

Sincosite (Idaho!)


Sincosite is a hydrated calcium vanadyl phosphate. (Schaller, 1922; Schaller, 1924). The mineral name recalls its type locality near Sincos, Peru. Sincosite strongly resembles metatorbernite. Investigation of a supposed metatorbernite specimen from South Dakota Zolensky (1985) led to the recognition of a second world locality for sincosite. Zolensky (1985) also provided the first X-ray powder diffraction data for sincosite, proposing a tetragonal unit cell. Determinations of the crystal structure of synthetic materials, Kang et al. (1992) and Franke et al. (1997) independently determined triclinic (but pseudo-tetragonal) symmetry, and also a lower water content than Zolensky (1985) or Schaller (1924), leading to the modern chemical formula for sincosite. Notably, triclinic symmetry is consistent with the biaxial optical sign noted in Schaller (1924).

Sincosite here forms square microcrystals to 0.5 mm. The matrix is a vanadium rich black shale. This locality has been reclaimed; no further specimens are forthcoming. A handwritten label accompanying the pieces reads "collected by Tom Loomis." Part of the Charles Trantham (1936-2020) estate.

Price: $60

Item code: MS1655

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