may have been dissolved away
Plate VI. Thin sections of quartzite.
Fig. 2 (upper half). Red quartzite of Prairie River Falls, Minnesota. No. 58 of the list, p. 35. Enlarged 31 diameters. Drawn to show the enlargement of a complex grain.
Fig. 2 (lower half). Cherty Potsdam sandstone, Westfield, Sauk County, Wisconsin. Polarized light. Enlarged 35 diameters. Cherty matrix holds grains of quartz which have received enlargements.
The appearance of the upper side of the largest quartz grain of the figure suggests that it may have been dissolved away. (p 18)
Figures (cropped from black surround) illustrating Roland Duer Irving (1847-88 *) and Charles Richard Van Hise (1857-1918 *) . On secondary enlargements of mineral fragments in certain rocks. Bulletin of the USGS. No. 8. 1884.
tags: R. D. Irving; C. R. Van Hise; dissolution; polarised light; quartz; rounds