The photomicrograph (cross-polarized light) shows a 2 mm wide part of a thin-section cut perpendicular to the primary brittle shear plane and parallel to slikenlines in mylonitized gneiss from near the Zanskar Shear Zone, Padam, western Indian Himalaya. Asymmetrically stacked muscovite grains interpreted as indicative of a top-to-SW sense of brittle shearing. In the absence of any other ‘markers’, the interpretation is based solely on the overall geometry of stacked grains, which is similar to the stacking of litho-units on larger scales in general (e.g., McClay and Insley 1986 and references therein), and also from other sections of the same shear zone (Mukherjee and Koyi 2010a, b). It should be noticed that the quartzo-feldspathic matrix, presumably more rigid, shows no evidence of thrusting. The smooth and straight margins of the muscovite grains indicate mechanical stacking rather than grain boundary migration that would result in irregular margins (Jessel 1987). The deciphered shear sense matches with those given by mesoscopic duplexes and thrust slices in the field scale (e.g., the supplementary field photograph). The core of the duplex structure (full arrow) shows extensive recrystallization of muscovite grains possibly during brittle shear. The exact mechanism of recrystallization is beyond the scope of this Geosite. The inclined white dashed line defines the northeasterly dipping axial trace of the anticlinal folded muscovite grains. Kinking is more prominent to the left of the axial trace. To its right, individual muscovite grains are thrust over each other and show curved (001) cleavage traces. Mica grains defining foliation planes are most vulnerable to duplex movement and can often be seen at very high magnifications. This seems to be the second report of a microscopic asymmetric duplex, see fig. 16.8 of Fossen (2010). Three phase of metamorphism that the Higher Himalayan Shear Zone enjoyed has been reviewed by Yin (2006).