American Mine (Alpha Copper Mine; Bridgewater Mine; Somerville Mine; Somerville deposit), Bridgewater Township, Somerset Co., New Jersey, USA
Latitude: 40°36'54"N
Longitude: 74°37'0"W
Ref.: NJ State Geologist's Annual Rpt. (1906): 146-148 (as the Bridgewater Mine); Rocks & Min.: 24:27-29; 63:130; Minerals of New York City & Its Environs, New York Mineralogical Club Bull. Vol 3, No. 1, Manchester, J.G. (1931): 35.; Cummings, W. L., 1998, Geology of the Chimney Rock Copper Occurrence, A Deposit Typical of the Watchung Basalts: In Puffer, J.H. Ed., The Economic Geology of Central New Jersey, Field Guide and Proceedings, Geological Association of New Jersey, fifteenth Annual Meeting, Pg. 29 – 49.
A copper mine located about 3 miles North of Somerville. Owned by the American Copper Mine Co. Featured the "Spencer slope" (1,300 feet long to the 600 foot level. The Mine exploited a conformable, copper-bearing horizon, generally 18 - 24 inches thick, in the upper most Passaic formation immediately beneath the Orange Mountain basalt. Copper occured mostly as thin veins, irregular small masses and sheets of native copper. The mineralized horizon has been darkened, mainly by recrystallization of hematite. This rock has been refered to as a hornfels but its origin appears to be due to hydrothermal fluids and not thermal recrystallization. Bleaching of the sediments almost always accompanies native copper. Chalcocite is much subordinate to native copper. It generally occurs in later veinlets that crosscut the copper and associated bleaching. Bleaching is rarely associated with chalcocite deposition but has been observed. The geology of the American mine is very similar to that of the Chimney Rock Mine (Cummings, 1998)
Restarted 1821 and closed about 1840, then reopened 1881 and closed 1910. A suburban house now occupies the site.
Mineral List
19 entries listed. 14 valid minerals.
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