[Rockhounds] N.J. has a volcano. Seriously! Here?s what you need to know.

[Paul]

A couple of papers:

Eby, G.N., Puffer, J.H. and Volkert, R.A., 2004. Petrology, 
geochronology, mineralogy, and geochemistry of the Beemerville 
alkaline complex, northern New Jersey. In Neoproterozoic, 
Paleozoic, and Mesozoic Intrusive Rocks of Northern New 
ersey and Southeastern New York, Twenty-first Annual 
Meeting Geological Association of New Jersey, Mahwah, NJ (pp. 52-68).
https://www.researchgate.net/publication/237746708_Petrology_Geochronology_Mineralogy_and_Geochemistry_of_the_Beemerville_Alkaline_Complex_Northern_New_Jersey
https://www.researchgate.net/profile/Nelson-Eby/publication/237746708_Petrology_Geochronology_Mineralogy_and_Geochemistry_of_the_Beemerville_Alkaline_Complex_Northern_New_Jersey/links/0c960521d70905f1a0000000/Petrology-Geochronology-Mineralogy-and-Geochemistry-of-the-Beemerville-Alkaline-Complex-Northern-New-Jersey.pdf

Aurousseau, M. and Washington, H.S., 1922. The nephelite 
syenite and nephelite porphyry of Beemerville, New Jersey. 
The Journal of Geology, 30(7), pp.571-586.
https://www.journals.uchicago.edu/doi/pdf/10.1086/622945

Yours,

Paul H.