Journal
CANADIAN MINERALOGIST
Volume 44, Issue -, Pages 959-965Publisher
MINERALOGICAL ASSOC CANADA
DOI: 10.2113/gscanmin.44.4.959
Keywords
tourmaline; dravite; magnesiofoitite; electron-microprobe data; Athabasca Basin; Saskatchewan
Categories
Ask authors/readers for more resources
Two generations of tourmaline have been observed in the matrix of altered breccias associated with the uranium deposits of the Athabasca Basin, Saskatchewan, Canada. The earlier tourmaline occurs as isolated crystals, whereas the later stage is represented by radial (or spherulitic) aggregates of fibrous crystals or overgrowths on earlier tourmalines. Tourmaline in associated veins closely resembles the late-stage tourmaline in the matrix of brecciated rocks. Atom proportions (based on electron-microprobe data) normalized to 15 Y + Z + T cations suggest that the earlier tourmaline is partially deprotonated, whereas the late-stage tourmaline is highly alkali-deficient. Assuming a stoichiometric content of boron, the structural formulas calculated for early and late-stage tourmalines from Rabbit Lake (sample R81) are: Na0.48K0.01Ca0.51 (Mg2.48Fe0.213+Mn0.01Ti0.24) Al5.34Fe0.663+ (Si-6.06)O-18(BO3)(3)(OH)(2.68) and square 0.76Na021K0.01Ca0.02 (Mg2.15Fe3+ Al-0.05(0.80)) Al-6.00 (Si5.89Al0.11)O-18(BO3)(3)(OH)(4.01). Similar compositions have been observed at the Second Link Lake and Key Lake uranium deposits. Early-stage tourmalines consist of proton-deficient dravite, whereas the late-stage tourmalines are close to the magnesiofoitite end-member of the tourmaline group.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available