Herkimer Diamonds

Herkimer Diamonds  are doubly terminated quartz crystals found in Herkimer County, New York and surrounding areas. These crystals have the typical hexagonal habit of quartz but are doubly terminated, making them quite rare and thus popular with mineral collectors.  The crystals are also used in jewelry because of their beautiful and interesting natural facets . Considered to be the most powerful of all quartz crystals, some people believe in their.metaphysical and healing properties.

Although similar double terminated crystals have been found in other locations like Arizona, Afghanistan, Norway, Ukraine and China, they could not rightly be called "Herkimers" (why???). Considering these unique crystals can be found so close to Kayuta Lake, it would seem such a shame to waste an opportunity to experience mining them first hand.

So, a few days ago, we went to the Ace of Diamond Mines and Campground, one of the 2 commercial mines in Middleville NY (the other one is Herkimer Diamond Mines). The $9.50 entrance fee per person allowed us to enter the dig area and to bring home any diamond or rock specimen we find.

Herkimer diamonds are found within cavities in the Cambrian-age, Little Falls Dolostone which was deposited about 500 million years age.  The most successful method of mining is "cavity prospecting", that is, breaking into large cavities in the walls and floors of the exposed dolostone using sledge hammers and wedges. The dolostone is a very hard rock and we did not have the tools nor the know-how for such a serious undertaking. Power tools are not allowed in this mine or the other.

We tried a little bit of "scavenger prospecting", which means just to search the rock rubble or quarry floor for exposed or loose crystals.  This was how the Mohawk Indians (who were known as Kanyenkehaka,  or The People of the Crystals) first found the crystals loose in the soil. Supposedly, some nice crystals can be found this way, but not by us.


Armed with our small tools (a regular hammer, small sledge hammer, a chisel), we did mostly "find and break" prospecting- that is, to find rocks already broken off from the quarry wall and breaking them into smaller pieces. It was hard work and a little dangerous, what with all the sharp pieces of rocks flying at each strike of the hammer.  We were glad we followed the mine's advice to wear safety goggles, long pants and shirt.



Although initially frustrating, after 3 hours of prospecting, we had some interesting finds starting with this broken rock which revealed a cavity with a few pieces of the clear crystals. Small, but definitely herkimers.

Our best find, however, was this one (shown on the left after we've brought it home).







The crystal had a fracture line and easily dropped out of the mother rock. Although the herkimer diamond is stronger (rated 7.5 on the Mohs scale) than other quartz crystal (rated 6.5-7.0), it's not as strong as a real diamond (rated 10).  It was about 2 cm in length but was not perfect in that it had a smaller crystal attached to it.  There are several inclusions, some clear and some golden in color.





At the end of the day, we felt satisfied with out find, our first mining expedition.  Whether there'll be a next one, that remains to be seen.