Abstract

Cloudy blue green, yellow, and white spongy mineral aggregates are common in the heavy mineral fractions of sandstones from widely scattered areas in the South Island, New Zealand. In many grains the color can be recognized only in incident light; in transmitted light, the cloudiness is observed only as a whitish brown gray. X-ray diffraction powder photography of individual grains shows that 1) blue green grains are pumpellyite and quartz, or pumpellyite alone; such grains show pleochroism from blue green to colorlessness; 2) yellow grains are epidote and quartz, less commonly with albite and chlorite; 3) white grains are dominantly either pumpellyite quartz or epidote quartz. Material of each of the three colors is widespread in the indurated Torlesse basement sediments and in many Tertiary sediments derived from them but less common in Upper Cretaceous and Lower Eocene sediments. This may have resulted from intrastratal solution, or else Torlesse rocks have been available for erosion only since the Late Eocene.

You do not currently have access to this article.