Chalcedony from Mines and Deposits in the Herkimer Mining District
The chalcedony quartz is generally not very commonly a well developed (or preserved) mineral episode in the the host limestone rocks that are the birthplace of the Herkimer diamonds. And when it does occur it is often covered over by quartz or other minerals. This has made it quite difficult to identify until 2015 when I saw the new stalagtite finds from the the Paradise Falls deposit. That helped to put into place other features I hade seen throughout the district. It’s pretty easy to get a myopic view about Herkimer diamonds if you’ve worked only one mine (or area).
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Chalcedony Shows Variation Across the District
The chalcedony quartz, when it is found not totally covered by latter quartz, shows quite a bit of variation. At DA it appears as a thin layer, most often white, on top of phase one druze. At TCR it is well developed, at times .5cm thick, and forms rounded mounds that look like “snow balls” when white. An interesting occurrence at TCR was a turquoise colored chalcedony looking material which may have been chrysocolla.Paradise Falls will likely yield spectacular specimens of chalcedony sometime in the future. The stalagtite form, often black as opposed to the white domes from TCR, can reach 5 cm in length. There can be multiple stalagtites on one specimen with some curving into one another. I expect to be adding more images to this page in the near future.
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Dr C will presentHerkimer Diamond Discoveriesat the 2017 Herkimer Diamond Festival