how do michenerite form?
<answer> Michenerite forms anhedral to subhedral rounded grains, rarely skeletal, in pyrrhotite and chalcopyrite or at their contact with rock-forming silicates. <context> Michenerite forms anhedral to subhedral rounded grains, rarely skeletal, in pyrrhotite and chalcopyrite or at their contact with rock-forming silicates (Fig. 11 a–c). Michenerite is the most abundant of all PGMs at Ransko. Grains range in size from 8 to 25 µm. In reflected light, the mineral is white with a faintly grey tint. Michenerite contains commonly higher contents of Fe and Ni (up to 1.6 and 1.3 wt%, respectively; Table 2). An extremely high content of Sb (up to 7.4 wt%) was found only in one sample. Fig. 11a–f.