Weddellite

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Weddellite

Description

A white, glassy mineral composed of Calcium oxalate dihydrate. Weddellite, and Whewellite, are two calcium oxalate minerals which form on the surface of carbonaceous minerals in the presence of microbiological organisms such as lichens. The mineral obtained its name when small crystals of weddellite were found in the sediment of the Weddell Sea near Antartica.

IR-ATR spectrum of Weddelite; Credit: RRUFF
Raman spectrum of Weddelite; Credit: RRUFF

Synonyms and Related Terms

weddelite (sp); calcium oxalate; wedelita (Esp.); weddelite (Port.); Weddelit (Deut.)

Physical and Chemical Properties

  • Colorless, transparent, tetragonal crystals.
  • Luster = vitreous
  • Streak = white
  • Fracture = conchoidal
Composition Ca(C2O4)-2H2O
Mohs Hardness 4.0
Density 2.02 g/ml
Molecular Weight 164.13
Refractive Index w=1.523, e=1.544

Resources and Citations

  • M. del Monte, C. Sabbioni, G.Zappia. The origin of calcium oxalates on historical buildings, monuments and natural outcrops. The science of the total environment 67, (1987), pp. 17-39
  • B. Ford, I.MacLeod, P.Haydock, "Rock art pigments from Kimberley region of Western Australia: identification of the minerals and conversion mechanisms." Studies in conservation 39, no. 1 (1994), pp. 57-69

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