Need a few notes
It is from the Maurice Black Stratigraphy Collection at Sedgwick Museum. It was collected from a borehole at Aislaby, near Whitby, Yorkshire and is part of the Permian evaporite sequence.
Rotation 1 - anhydrite, but with a blocky gypsum crystal at the margin and a small spray of crystals (grey/pale yellow in XPL). Note lower relief of gypsum.
Rotation 2 - mainly anhydrite