Staurolite is a common mineral in pelites of medium metamorphic grade.  Views A and B (at right angles to each other) illustrate the pale yellow to yellow-orange pleochroism of staurolite, which has high positive relief relative to the quartz-muscovite matrix and quartz inclusions.  The two adjacent subhedral poikiloblastic grains in C with different orientations show different shades of yellow, and in D illustrate first order yellow interference colours, near the maximum for this mineral.  A and B are from an unknown location and C and D are from the Odjick Formation, Wopmay Orogen, N.W.T., Canada.  All views are 5.5 mm across.  A, B, C ppl, D x-nicols.