Hand sample showing large equant crystals with random orientation. Some appear to be twinned. Crystals are now sillimanite pseudomorphs after andalusite. See t.s. below. Sample is a pelitic rock from the margin of Wolf Mtn. Intrusion. Cm. scale in photo.

This pattern of near parallel sillimanite crystals (yellowish) forming a tabular shape is characteristic of sillimanite replacing andalusite (Vernon, 1987, Canadian Journal of Earth Sciences). CPL, long axis approx. 12 mm. From rock similar to hand sample shown above.