Detrital grains of garnet in sandstones very commonly show a peculiar surface feature that has been observed by a number of workers in sedimentary petrography, but it has been only briefly mentioned in the literature as an unusual condition and generally misinterpreted. Actually the peculiarity is very common and therefore merits more consideration. In the Tertiary strata of Venezuela garnet of this type is especially abundant and beautifully developed, being quite characteristic of certain formations. Since becoming interested in this material from Venezuela, the writer has observed it commonly in sediments from various localities. Several British petrographers have mentioned garnet that is evidently of this same kind but have considered the peculiarity as a cleavage developed in the garnet. However, Mackie1 noted its occurrence in the sandstones of Scotland and correctly attributed the result as due to etching.

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