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22 August 2003

Geologist for a Day: Trip to a Zinc Mine

by Mark Streitman

I love to travel and science travel is about as good as it gets.  Whether it's going to the Museum of Natural History, seeing a zoo, hiking through some great tidal basin or going to some place you didn't know existed, but turns out to be very cool!   This is one such place.  

The New Jersey chapter and some guests went to the Sterling Hill Mine  (http://www.sterlinghill.org/)   and the Franklin Mineral Museum (http://www.franklinmineralmuseum.com).  Does this sound like a class trip for an elementary school?  Well yes, it does and they do get lot of trips from schools.  However school kids generally don't appreciate the cool learning experience it is.  In this case, going to these two sites managed to combine geology, history and mining technology all in a day's outing.  

Our group originally wanted to go to a cave.  Not a tourist cave, but a cave that had no special setup for people. We would have gone with cavers that knew what they were doing, but there were legal problems ( just think of various lawyer and politician jokes and you get the idea) .  So some of our members thought of the idea of going to this mine and museum.  We voted and agreed to meet there for the tour.

So last Saturday we met at Ogdensburg, NJ to visit the Sterling mine/museum.   This was a real working zinc mine and closed in 1986.  It was then taken over by a non-profit group to be run as a museum and has been open to the public since 1990.  

Believe it or not this area of New Jersey is considered one of the most geologically diverse places on earth.  Now I find that hard to believe, since I doubt every square foot of the planet has been analyzed to make that determination. So what people must really mean is that it's most geologically diverse place that has enough people near it to explore it thoroughly.  It's only one hour from New York City.   The area has been mined since the 17th century and the Lenni Lenape Indians may have mined it before that.  

 

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We began at the Mine tour office.

Our tour guide had a lot of experience with the mining industry and so made the tour very interesting. The cages were used to hang the miners clothing on to dry over night.

 

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We started at the Sterling Museum first.  This showed a lot of the history of mining in the 20th century. Both in the technology and the human experience.  Here are a few photos of some of the exhibits in the museum.

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Dinosaur footprints    (above)

Below is a photo of some of the rocks that were pulled out of the mine. The three most common minerals in the mine were Franklinite - a zinc iron manganese oxide, Willemite, a zinc silicate and  zincite. There are over 300 other minerals found in the area.  Franklinite and zincite are not found almost anywhere on earth.

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They also had a gold mineral exhibit and fools gold so you can tell the difference in case you ever need to know.

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We then proceeded to the mine.   Here is our group waiting (about half is our group) to enter the mine.

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Our first view inside the mine is what one would expect.

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The pipes in the photo are water and compressed air to run the tools.

Since this mine is over 100 years old, there are various technologies that were used to dig it out. Some of the tunnels were dug by hand, some were blasted and hand removed, some were blasted and machine removed. Some of machinery that is shown is modern and some are antiques.

This photo is of a miner from 100 years ago.

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Notice the helmet light, it's a Carbide Lamp, it works by a chemical reaction of water and a carbide to produce a gas.  The gas came out the top front and was lit to produce light. I found a web site that explains this better .

Apparently invented by Thomas Edison, the electric miners light came into regular use in the 1920's and modern ones use large battery packs to last a whole work shift.  This photo is of a modern miner and the next one is of the battery charging room.

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The next photo is of the various drills used, it can't be seen in the picture but the drills that they show start out with solid metal ones  from 100 years ago that blew rock dust into the miners face and their lungs.  They didn't have long careers.  All the way to modern drills that are hollow, diamond tipped and use water to take away the dust. It's a lot safer a profession now, but you really come to understand that it's just as dirty, cold and hard work down in a mine.

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Mines were mini railways that were used to haul the ore out of the mine.

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Apparently modern mines use mini trucks to do the same task.

Here are two more photos of the mine itself.  The first shows how blasting was and is done.  First holes are drilled into the rock face and then explosives are inserted, next groups of holes are numbered and detonated in order with specific time delays.  In the old days they did this my hand, but I would think today they use some kind of computer controlled detonation process( I didn't think to ask).  After a section is blasted, the loose rock gets pushed down a shaft to a mine car on a lower level. The second photo is one of the oldest and narrowest tunnels because it was made only with hand tools.

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Next time:The Franklin Mineral museum, Fluorescent rocks and shortwave ultraviolet.