A black Herkimer Diamond is defined as a Herkimer crystal with a good amount of black material contained within the gem. Traditionally, this black material was called Anthraxolite. A relative of anthracite (coal), decayed plant material that fossilized.
new evidence suggests this smoky black material was caused by hydrocarbons verses anthraxolite. A hydrocarbon is a thick oily substance. The new theory suggests that hydrocarbons moved through the cracks and vugs along with dissolved quartz, salt and other minerals. At some point these fluids solidified, providing the areas to grow Herkimer Diamonds. This black substance can also be
found in the pockets surrounding the Herkimer's.
This group of black Herkimer Diamonds range in size from ¼" to ¾", most are around ½". Sizes and descriptions:
- A 6.5x4.5x4 mm with excellent clarity. The hydrocarbon is completely encased; cool with a loupe.
- A 9.5x5x4.5 mm with encased hydrocarbon.
- The 10x6x4.5 mm is a tabby crystal.
- This 11x4.75x3.5 mm has a cool, long shape and excellent clarity.
- An 11.5x7x5.5 mm with 2 tiny bridge crystals.
- An 11.75x8.5x5.5 mm with great clarity and well defined key mark.
- The 12.75x5.75x4.75 mm is another with a long unusual shape.
- A 14.5x9x8 mm with great clarity and completely encased black hydrocarbon.
- The 19x9.5x8 mm has a dark, oil slick like rainbow.
- With hydrocarbon internal and external, a 22x15x12.5 mm has good clarity.
- A 22.75x14x11 mm similar to the one above.
All have sharp double termination points. It's a well rounded group of black Herkimer Diamonds.