Herkimers

 

last modified: Sunday, 19-Jul-2009 16:10:06 CEST

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Herkimers are found in the area around the City of Herkimer, south of the Adirondack Mountains in New York State.
They have been searched since the 19th century, but commercial "mining" as a tourist attraction has started in the 1970s.

Note: I should mention that "Herkimer" is not a trademarked name and very often you will see offers of similar material from other places, e.g. China.

 

Collecting

There are a number of fee collecting sites that can be looked up easily in the Internet. In early April 2003 I made a 2 day trip to Herkimer to check it out myself and visited the "Ace of Diamonds Mine". That early in the year, and on a weekday, not much was going on, I was one of the few seasonal early birds.

There are essentially two ways of collecting:

1. The Easy Way

You can work through the loose rocks that lie around and have been piled up by the mine workers. The prospect is good, but you need to be patient, as these rocks contain only small pockets, and most of them are empty.
I rented a few heavy tools from the mine owner (I only took my Swiss Strahlstock with me on that trip to the US, but here it was completely useless). The most important tool (which I foolishly only picked on my second day) is a strike hammer to split the tough rock. A small hammer alone won't do it. Just look for a large rock that shows signs of anthraxolite and split it. Sometimes the crystal remains inside the small pocket and you get a nice matrix piece. But most of the time, enclosed crystals will just pop out, usually being up to 2 cm in size. I also found 2 small clusters of crystals, one still in place. Occasionally a pocket is still filled with water. Whatever you find, in the evening you will feel your back.
This is what most people do, and I did that, too, because the second method is much more time consuming.

2. The Hard Way

You can work on the rock wall itself and try to open one of the big pockets. From what I've heard from people at the quarry, you should expect this to take a couple of days.

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The first picture (I must apologize for the bad image quality of the 3 pics) shows a small portion of the wall. The holes you can see at the base of the wall are emptied pockets. The guy on the right side was just done with a pocket that is hidden under the blue plastic blanket.
To find a pocket, people check the rock at the base of the wall; e.g. they might strike a hammer against the rock to see if it sounds hollow, that being an indication of a pocket behind. In theory, you could "go in" just anywhere, as the pockets are about 20-40 cm wide and about 1-2 m apart.

The "mother load" is at the base of the wall because legions of rockhounds have slowly removed rock from the wall and of course did not dig deeper than necessary, so the wall slowly moves backwards along that layer.
Digging in starts at the top of the wall, removing a portion of the first layer, then the next layer, and so on till you get to the base. The guy standing on top of the wall is just about to begin his way down the wall, removing soil with a shovel.
Every rockhound probably removes a metric ton or even more of material from the wall. The rock is really tough, but when the going gets tough...


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The next picture shows the pocket hidden under plastic in the first picture. It has been worked on for about a week.
The real purpose of the plastic cover is unclear to me, so I can only guess that its use is both to mark a "claim" and to act as a sun shield to prevent the freshly removed and cold crystals from cracking by warming up too quickly.
I was too late to take pictures of the many crystals removed from it, but the rockhound was still working on something.

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What he finally got after 2 days can be seen in the last picture. It is an outstanding single crystal of exceptional size, a bit smoky - probably from inclusions of anthraxolite - and showing nice skeletation on its faces. It was still dirty but looked very promising. A piece like that is somewhat uncheap. While most crystals lie loose in the pocket, some of them can be attached to the walls or an anthraxolite matrix. You can tell from the swollen and bloody hands that dealing with nice quartz points has its drawbacks.

So the reward of such an effort can be substantial, and if you browse around on the Internet, you will find stories of people bringing home buckets filled with herkimers.
But beware: you will never find a story of those who didn't...

 

Specimen

The images I present here are - with one exception - all from crystals that have been found in loose rock, and not from the large pockets at the base of the wall. While you don't get the big stuff that way, you can take home a crystal on matrix, which is rather difficult to do with an entire pocket, although not impossible: You can see a complete pocket at the Smithsonian Museum in Washington, D.C.



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An  idiomorphic crystal in a small cavity. On the lower right side you will notice an s crystal face.
All crystals shown on this page have developed one or more s faces. Many of them show them on both ends of the crystal, and on alternating positions (3 s faces on each end), indicating that they are untwinned. To be sure, I would have to perform a few optical tests with them.

Most crystals have no striations on the m prism faces. This is very different from rock crystal found in alpinotype environments, and is one of the reasons why Herkimer crystals appear so clear.



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Some  of the small pockets do not contain double terminated crystals but "ordinary" rock crystals. This is not what people are after, but it's still nice. There is no anthraxolite in these pockets. You can also recognize some rhombohedral dolomite crystals.


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Another  example of an ideally shaped (idiomorph) crystal.


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The  irregular pattern below the center of the crystal with black anthraxolite attached to it indicates where the crystal was touching the wall of the pocket.


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The  hexagonal stair-like pattern at the lower center of the crystal is generated when another crystal that was attached to it got off. It can be seen on many Herkimers, whereas usually separating crystals from each other would result in ugly irregular or conchoidal fractures. The anthraxolite attached to the wall of the cavity looks very much like liquid tar or pitch, but is solid.


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Herkimers  don't need to be colorless. Some of them are covered by a thin layer of iron oxides that gives them a yellow tone which contrasts nicely with the gray of the host rock.


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This  is a crystal that the rockhound who found the big crystal in the third picture on top of this page gave me. It is from the same large pocket and about 4 cm long. You can see small liquid inclusions near the surface of the prism. These bubbles sometimes let the crystals crack as they warm up after being removed from the cool pocket.


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Three  clustered but loose crystals in a small pocket.


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A  group of very small intergrown crystal.

 

Further Information, Literature, Links

Information about the general geology of Herkimer County and the genesis of the crystals can be found in an ->article by W. Ulrich.

W.D. Hoisington has collected a lot of photos and information on localities, theories of formation, inclusions, etc. on the website www.herkimerhistory.com.


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