Suggested Citation
Lapham, D. M., and Gray, Carlyle, 1973, Geology and origin of the Triassic magnetite deposit and diabase at Cornwall, Pennsylvania: Pennsylvania Geological Survey, 4th ser., Mineral Resource Report 56, 343 p. [Available online.]
Description
The Cornwall iron mine in Lebanon County, southeastern Pennsylvania, has a long economic history extending from its importance to the Revolutionary War and continuing up until the early 1970s. The genesis of the ore body is a complex weave of mineralogic changes brought about by the intrusion of diabase into the limestone country rock. Coupled with the tectonic setting, the Cornwall deposit can be traced through different phases of metamorphism and mineralization. It is an interrelated story that can provide a unique perspective into this and other “Cornwall-type” occurrences in Pennsylvania. The text is complemented by a list of minerals, results of chemical analyses, and separate geologic maps and sections across the ore bodies.