Figure F18. Rounded black tachylitic volcanic fragments with microlitic texture, and birefringent brown clay minerals (altered volcanic glass) (Sample 149-897C-62R-1, 123 cm). Porosity (blue) is likely a product of shrinkage of swelling clay minerals during thin section production. White areas (plane-polarized light) are where softer clay was gouged out during thin section preparation. A. Plane-polarized light. B. Cross-polarized light.

Figure F18. Rounded black tachylitic volcanic fragments with microlitic texture, and birefringent brown clay minerals (altered volcanic glass) (Sample 149-897C-62R-1, 123 cm). Porosity (blue) is likely a product of shrinkage of swelling clay minerals during thin section production. White areas (plane-polarized light) are where softer clay was gouged out during thin section preparation. A. Plane-polarized light. B. Cross-polarized light.