10 Volcanoes in New Jersey?

One of my new hobbies is rock collecting and geology. Rock collecting (or rock observing where collecting is not allowed) is a relatively cheap hobby, and it gets me out of the house which is healthy for the mind and body.

New Jersey is famous for fluorescent minerals, like willemite, found in the Franklin, New Jersey area. I was thrilled to learn that New Jersey has fluorescent minerals outside of the Franklin area, like sodalite in the Beemerville nepheline syenite mass. Around the same time I learned of the sodalite, a family member sent me a link to a story about the New Jersey volcano, Rutan Hill.

I downloaded Google Earth and installed a KMZ file of New Jersey geological data to check out the volcano and the nepheline syenite mass where the sodalite is found.

The pink areas are the nepheline syenite, the red areas are ouachitite breccia, and the “R” is the Rutan Hill volcano. The USGS page about ouachitite breccia says it is found chiefly “in numerous diatremes in the Beemerville area; largest of at Rutan Hill.” Diatremes, “are sometimes known as a maar-diatreme volcano” (quoting Wikipedia). If Rutan Hill is a diatreme volcano, the rest of the red areas below are probably also diatremes. Counting the red areas on the map, there are 10 “volcanos” in New Jersey. Not active volcanos, but old ones nonetheless. Cool. Now I want to buy a house on one of them. Interestingly, Grammarly wants me to change “on” to “in”. I don’t want to live “in” a diatreme, Grammarly.

10 Volcanoes in New Jersey

You can see some of these features in Lidar data as well. This is not the same scale and area as the Google Earth map:

Lidar Hillshade


My favorite Geology resources

A hunk of mostly microcline feldspar from Franklin, NJ, sitting on my desk:


Listing my favorite Geology resources. Many of these are just for fun.


Nick Zentner: focuses on Washington state, but at the same time, he’s probably the best popular science educator at the moment. His YouTube channel amazes me. I’ll probably never visit Washington state again (I’ve been to Seattle twice) but I still watch all of his videos. His Baha BC series is my favorite “TV Show”.

Skye Cooley is good for information about ancient cicada tunnels in soils.

Myron Cook is good for field geology and the western United States.

Shawn Willsey has great geology 101 information and excellent deep dives on Idaho geology.

The USGS YouTube channel is great, even if you just want to watch a volcano in Hawaii erupt for hours on end.


Mindat is excellent for finding old mines and rock-hounding locations. good foundational information.

USGS Geological Maps of the US. I like importing KMZ data into Google Earth. And then I buy the paper maps on eBay.

USGS Publication Warehouse. I like downloading old documents and then buying the on eBay.

I’m in New Jersey at the moment so NJ Geographic Information Network is a great resource. As is the New Jersey Office of GIS for lidar info.

I follow some mining industry people like Peter Bell on Twitter. What they do is interesting, but I’m not after gold.

The Sterling Hill Mining Museum in New Jersey. Fluorescent rocks and zinc mining.

Franklin Mineral Museum. Fluorescent rocks and zinc mining. I’m a lifetime member.

The Franklin-Ogdensburg Mineralogical Society, Inc. (FOMS).

North Jersey Mineralogical Society is worth joining if you are in New Jersey, New York City, western Connecticut, southern New York, or eastern Pennsylvania.

ChatGPT Geology

Chatting with ChatGPT about mining and Zinc

Yesterday I was chatting with ChatGPT about New Jersey mining and zinc ore. is a better source of this information, but I was curious about ChatGPT’s knowledge.

Her response to a list of mines in New Jersey is very good, especially from the perspective of a hobbyist, historian, or local rock hound. There are active mining activities in New Jersey, but they are purposely not “well advertised”, so I cannot fault ChatGPT for not knowing about them. Mostly sand mining — sand for concrete needs to come from somewhere, and a lot comes from New Jersey. Other than Sterling Hill & the Franklin mines, I think Hibernia is worth mentioning because it is visually impressive, and it is fun to visit.

New Jersey was not a major mining state and there were a limited number of mines historically. Here is a list of some of the known old mines in New Jersey:

  1. Sterling Hill Mining Museum: located in Ogdensburg, it was a zinc mine that operated from the late 1700s to 1986.
  2. Franklin Mine (museum): located in Franklin, it was a zinc and iron mine that operated from the early 1700s to 1954.
  3. Bevans Mine: located in Andover, it was an iron mine that operated from the early 1700s to the late 1800s.
  4. Furnace Hill Mine: located in Andover, it was an iron mine that operated from the early 1700s to the late 1800s.
  5. The Mine Hill and Schuyler Copper Mine: located in Franklin, it was a copper mine that operated from the early 1700s to the late 1800s.
  6. The Copper Mine Hill: located in Mine Hill it was a copper mine that operated from the early 1700s to the late 1800s.
  7. The Morris Canal & Mining Company: located in Ledgewood it was a mining company that operated from the early 1800s to the early 1900s.
  8. The New Jersey Zinc Company: located in Franklin it was a zinc mining company that operated from the late 1800s to the mid-1900s.
  9. The Sussex Mine: located in Hamburg, it was an iron mine that operated from the late 1700s to the early 1800s.
  10. The Beemerville Mine: located in Beemerville, it was an iron mine that operated from the late 1700s to the early 1800s.

It’s worth noting that many of these mines are not in operation anymore and most of them are not open to the public. Some of them may have been converted into museums and open for visiting. Also, the information of these mines may be limited, and some others may have existed in the past but information about them is not well documented.

Historically, New Jersey was an important resource for iron, in the form of bog iron, clay for pottery, zinc, gravel, and sand for construction. Other than sand, it’s cheaper and more efficient to find these minerals and rocks elsewhere.

One challenge for the mining industry in New Jersey is most of the land is protected, or covered with sprawling residential neighborhoods, which are difficult to have removed, though in some cases I would like to. If I had Elon Musk’s type of money I would buy all of Parlin, New Jersey, and mine it for amber, clay, and lignite — maybe not mine it, just enjoy it from a rock collector perspective.

Here’s a hunk of zinc ore from Sterling Hill:

Zinc Ore

I also asked ChatGPT for a list of zinc ores. Three of them appear in the rock above.

Here is a list of zinc ores:

  1. Sphalerite (zinc sulfide)
  2. Smithsonite (zinc carbonate)
  3. Hemimorphite (zinc silicate)
  4. Calamine (hydrated zinc carbonate)
  5. Willemite (zinc silicate)
  6. Franklinite (an oxide of zinc, manganese, iron and nickel)
  7. Hydrozincite (hydrated zinc carbonate)
  8. Zincite (zinc oxide)
  9. Zinkenite (a sulfide mineral of zinc and lead)
  10. Siderite (iron carbonate) that contains zinc as impurity

Please note that this list is not exhaustive and there may be other zinc ores that have not been included here. Also, The amount of zinc that each ore contains varies greatly, depending on the location and quality of the deposit.