ES2 Metamorphic Rocks
Dalradian Metamorphic Zones
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Biotite zone (Sample 108)

The assemblage is Bt + Chl + Ms + Ab + Qtz, with minor calcite and accessory opaque oxide (magnetite) and tourmaline. Biotite mostly forms blocky, randomly-oriented porphyroblasts up to 1 mm across. The matrix consists of fine-grained (up to 0.1 mm) granoblastic quartz and albite with strongly-aligned muscovite and green chlorite defining a schistosity. The schistosity is deformed into weak crenulations.

DJW - March 1999