Opal from Somerset County, New Jersey, USA
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| Kent, B.P. and Butkowski, B. (2000): Minerals of the Millington Quarry, Somerset County, New Jersey. Mineralogical Record, 31: 411. |
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| Speiser, Robert (1978) A Quest for New Jersey Minerals: 10.(privately published). |
Chimney Rock Quarry, Bridgewater Township, Somerset County, New Jersey, USA