	*Rankin, D.W. (1997) Geologic maps of St. John, U.S. Virgin Islands. Open-File Report* Vol. 1997 (97-472) US Geological Survey doi:10.3133/ofr97472**	Report (issue)
	U.S. DEPARTMENT OF THE INTERIOR U.S. GEOLOGICAL SURVEY GEOLOGIC MAPS OF ST. JOHN, U.S. VIRGIN ISLANDS...preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards or with the...purposes only and does not imply endorsement by the U.S. Government. 1997 DESCRIPTION OF MAP UNITS Dikes...porphyritic tonalite characterized by large bipyramidal quartz and barrel-shaped biotite phenocrysts. Groundmass...percent, of quartz, plagioclase, biotite, less commonly hornblende, and prominent apatite. Quartz and plagioclase
	*Rankin, Douglas W. (2002) Geology of St. John, U.S. Virgin Islands. Professional Paper* 1631. US Geological Survey doi:10.3133/pp1631**	Report (issue)
	Page 1 D U.S. Department of the Interior U.S. Geological Survey Geology of St. John, U.S. Virgin Islands...Rankin—GEOLOGY OF ST. JOHN, U.S. VIRGIN ISLANDS—U.S. Geological Survey Professional Paper 1631 U.S. GEOLOGICAL...Trunk Bay on the northern coast of St. John, U.S. Virgin Islands. Trunk Cay is located just to the left...Thatch Islands of the British Virgin Islands, and Mary Point, which is to the northeast on St. John. U... U.S. Department of the Interior U.S. Geological Survey Geology of St. John, U.S. Virgin Islands By Douglas

Quartz from Kiddel Point, St. John, U.S. Virgin Islands, USA