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A sapphirine-bearing granulite from the Snowbird tectonic zone, northern Saskatchewan, Canada.

Al (left) and Ca (right) maps. A peak metamorphic assemblage of garnet, quartz, kyanite and clinopyroxene has been extensively modified and replaced by sillimanite (masses at top of view) , plagioclase (strongly zoned, forming much of new matrix), sapphirine-plagioclase symplectites (fringing most phases) , corundum-plagioclase symplectites (among sapph-plag) and orthopyroxene-plagioclase symplectites (isolated, dark in the above view. Remnant garnet (bottom) shows profound zonation in Ca.

The map of Al covering the same area provides additional distinction between phases. Note particularly that the scale of the equilibrium domains may be less than 50 micrometers in this specimen.

For more information about this image contact: Michael L. Williams