Granite / Greisen, Topaz, Zinnwaldite. Germany

This is a thin section microscope slide of Greisen (altered granite) from Zinnwald, Saxony, Germany. From a tin mining area this is an altered granite containing fans of Zinnwaldite (the type locality, a type of mica), very bright colours in xpl, and Topaz of a type known as Pyknite. This shows characteristic basal parting, and some alteration in the cracks. Very Pretty slide.
This slide contains several large topaz phenocrysts, which are fragmented, apart from the natural preexisting basal partings. These topaz have proved difficult to preserve. Slide left very slightly thick for the same reason

1 Slide

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