The writer during the summer of 1928, while engaged in field work for his masterʼs thesis, encountered an occurrence of doubly terminated quartz crystals similar to those described by Tarr,1 but in this case they are replacing dolomite rather than gypsum. These crystals were found in a ferruginous sandstone of the Jonesboro formation three-fourths of a mile west of Elkton, Virginia. A like occurrence in the same formation had been noted by Mr. Charles Butts of the United States Geological Survey during the previous summer in the vicinity of Wytheville, Virginia. He submitted specimens of thatmaterial to Dr. A. A. Pegau of the Geological Department at the University of Virginia. The latter referred these specimens to the author, with the suggestion that he make a detailed study of their occurrence.