Unaligned, prismatic crystals of schorl, with strongly mauve to indigo pleochroism and concentric compositional zoning are scattered throughout the sample. Basal sections remain a deep blue regardless of rotation of the stage. A corona of clear tourmaline (perhaps) rims most grains. The tourmaline are found in a sericitized feldspars.
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This strongly layered rock is also strongly altered and microcrystalline enough for minerals to be indistinguishable. The layering is defined by alternating dark and light lenses. Frequently, elongated, flattened vesicles will have a lighter-colored rim. This thin section has a greasy-looking film on the surface that makes it difficult to focus clearly.
This fine grained sample is fairly monomineralic. The small, feathery crystals are aligned to form a weak foliation. Opaques are plentiful though sphene much less so.