The Petrographic Re-Examination of Quartz-Bearing Plutonites from Vermont

Abstract

Quartz-bearing plutonites from Vermont long have been known, especially those that are widely used as building stones. Invariably these rocks have been designated as granites, or more rarely as quartz monzonites. Usually they have been named from very general qualitative mineral analyses; and even if they were named from partial quantitative mineral analyses, there were very few cases in which the actual percentages of the various feldspars, so important in the modern classification of rocks, had been determined. From detailed, quantitative, mineral analyses it is suggested that the Dummerston white granite from the Black Mountain quarry might more properly be called a leucogranodiorite; the soda granite just south of Hardscrabble Corner, Springfield, a leuco-sodaclase-granodiorite; the biotite granite from the Boutwell, Milne, and Varnum Company's quarry at Barre a biotite-granodiorite; the biotite granite from the Mackville quarry south of Hardwick, a biotite-granodiorite; the Bethel white ...