Figure F19. Photomicrograph of typical texture in a strongly altered rock. Whitish gray reflective elongate crystals are acicular plagioclase. Less reflective areas tinged in red are microcrystalline calcite. A few more bright crystals are well-crystallized calcite. Nonreflective brown areas are mainly clay minerals. Most plagioclases are pitted and have slightly grayer interiors of secondary plagioclase that are jacketed by more reflective unaltered plagioclase (Thin Section 54; Sample 324-U1346A-14R-3, 34–36 cm). Reflected light.
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