Reports

Boron in Sillimanite

Science  05 Aug 1983:
Vol. 221, Issue 4610, pp. 547-549
DOI: 10.1126/science.221.4610.547

Abstract

Sillimanite in six granulite-facies, kornerupine-bearing rocks contains 0.035 to 0.43 percent B2O3 and 0.02 to 0.23 percent MgO (by weight). Substitution of boron for silicon and magnesium for aluminum is coupled such that the ratio of magnesium to boron is about 0.5. Sillimanite incorporates more than 0.1 percent B2O3 only at high temperatures in a boron-rich environment at very low partial pressures of water. In the amphibolite facies, the sillimanite boron contents are too low to appreciably affect the stability relations of sillimanite with kyanite and andalusite.

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