Mineral: Microcline
Locality: Hachupa, Shigar District, Gilgit-Baltistan (Northern Areas), Pakistan
Dimensions: Main crystal size: 10 x 6 x 6 cm

Description: This is the angle that I'm trying to measure (between green lines). It should be 89º but I'm unable to see any difference with a right angle (theoretically the orange line but in practice both lines coincide). With 1 degree and 30 mm of edge, deviation from a right angle should be about 0.5 mm, enough to be detected with my carpenter's square.

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