Tuffs are explosively erupted volcanic material that is consolidated and lithified after deposition. Tuffs may contain lithic fragments, glass shards, and/or broken mineral grains and have pyroclastic texture.
The photos above (crossed polarizers on left, plane polarized light on right) show lithic crystal tuffs containing twinned, broken plagioclase clasts, and altered lithic clasts (right side of photos), in a matrix of very fine-grained material.
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