stripes
The Peabody granite forms an oval stock of 8.5x5.5 km cutting Salem gabbro-diorite, and gneisses and amphibolites of the Marlboro Formation. The granite is a uniform, coarse grained rock of perthite, quartz, an iron-rich amphibole, with about 10% arfvedsonite molecule (Toulmin, 1964, p. 32), aegirine-augite, which commonly has sheaves of riebeckite around it, a little biotite, zircon and apatite. Possible pyrochlore and lamprophyllite have been observed. Chemical analyses for a range of trace elements, including REE, in rocks and minerals will be found in Buma et al. (1971).
BUMA, G., FREY, F.A. and WONES, D.R. 1971. New England granites: trace element evidence regarding their origin and differentiation. Contributions to MIneralogy and Petrology, 31: 300-20.
CLAPP, C.H. 1921. Geology of the igneous rocks of Essex County, Massachusetts. Bulletin, United States Geological Survey, 704: 1-132.
LYONS, P.C. and KRUEGER, H.W. 1976. Petrology, chemistry, and age of the Rattlesnake pluton and implications for other alkalic granite plutons of southern New England. Memoir, Geological Society of America, 146: 71-102.
TOULMIN, P.III. 1964. Bedrock geology of the Salem Quadrangle and vicinity, Massachusetts. Bulletin, United States Geological Survey, 1163-A: 1-79.
ZARTMAN, R.E. and MARVIN, R.F. 1971. Radiometric age (late Ordovician) of the Quincy, Cape Ann, and Peabody granites from eastern Massachusetts. Bulletin of the Geological Society of America, 82: 937-57