Three textural types of exsolved chromites. Type A grains consist of an Al-rich host that contains blebs and rare smaller lamellae of an Fe-rich guest; type B grains have an Fe-rich host that contains blebs and dense networks of lamellae of an Al-rich guest; type C grains contain a very fine intergrowth of Al- and Fe-rich lamellae. Miscibility gap in the spinel prism is tunnel-shaped and extends from the Fe 3 O 4 -FeAl 2 O 4 -FeCr 2 O 4 face to the MgFe 2 O 4 -MgAl 2 O 4 -MgCr 2 O 4 face. If exsolution began at or near the peak temperature of regional metamorphism in the eastern Beartooth Mountains, the temperature of unmixing was near 600 degrees C.--Modified journal abstract.

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