Chlorites with high values of Mg/(Mg+Fe), close to the end-member “clinochlore” are not as strongly pleochroic as are Fe-rich chlorites, and also do not have anomalous interference colours.  In the variety of orientations of the chlorites in A, only faint pleochroic colour variations are evident, and in B the “normal” interference colours of first order white are apparent in the polysynthetically twinned chlorite, which is superficially similar to plagioclase twinned according to the albite law. Sample is a chlorite-pargasite rock from Moses Rock diatreme, Utah.  Both views are 2.2 mm across.  A ppl, B x-nicols.