This site was last updated on May, 2011
Quartz Crystal Habits within Herkimer Diamond Deposits
Definitions and Scope:
The best website on "Herkimer Diamonds"
Larger photos of the thumbnails presented on the main "Crystal Form" page. Included is identification information and the source link is embedded there (just click). In some cases additional information and comments are provided for each photo.
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Photos, and videos, of "in place" Herkimer bearing pockets
Photos from Bill and Anne, submitted Sept. 2008. In this pocket you can see one crystal on the lower right, the rest is mud and hydrocarbon (the black stuff). This is Middleville, NY (AD). Below (right) is a closer shot showing the clay rich mud around the crystals, and on the left a more distant shot of the zone with two open pockets, just above the shade.
Links to sites with photos of "in place pockets":
Herkimer diamonds occur (mostly) within openings in the host rock. These openings are called "vugs", when having one or two crystals, or "pockets" when they alot of crystals. Occassionally collectors will photograph these "in place", meaning right where they sit in the ground. Here you can find links (white blocks below) to such pictures, and this author's comments (in white lettering).
This link above is excellent in showing the opening of one type of Herkimer diamond pocket at one location - note pockets behave a little bit differentely at each loaction. This is a large a mud filled pocket, partially collapsed, and well shown in a series of photos. In addition the author has provided informative comments. Mud or clay minerals (found in mud) are associated with carbon material (in varying degrees) and Herkimer diamond pockets. The amount of clay, versus hydrocarbon or almost nothing, in a pocket is variable from one location to another even within the same quarry/mine. Much of the clay came into the pockets along with the hydrocarbon and can be found interlayered with it (see ).
There is also frequently a top to bottom zoning in larger pockets containing heavy clay, or heavy hydrocarbon material, with the larger amount of quartz crystals found on the bottom. This zoning is found across deposits in the Herkimer district and is particularly noticable the Hanson/Benchmark quarry, where the walls of the pocket are fresh and intact. This top to bottom zonation is probably more common than collectors realize, with many pockets (even small ones) having most of the larger Herkimers on the floor - even when not collapsed. It is true that since the last glacier ground water has moved through the rocks and caused changes to the rock, and to the pockets, but that is only part of the story. Some mud most likely moved around during that time, and frost/freezing had its effects, but clay mineral deposition is an important part of the history of Herkimer diamonds. Most skeletal crystals contain clay layers inside the crystal (see ) and all the deposits in the region contain some clay in association with the the hydrocarbon material. It is another piece of the tale Herkimer diamonds have to tell us.
submitted by Jeffery B. Fast
Also some nice mineral photos
The photos in the above link clearly show the "pocket layer", and there is a nice discussion about pocket spacing (although no explanation to why this spacing occurs). There is also mention of the "table", a field collecting term referring to the the flat surface that is usually followed to discover pockets. There is likely an explanation for why a "table" is linked to the pockets. In addition one of the pictures shows a pile of rock debris that was moved - note the block nature of the material in the debris pile. All of the field information shown in this excellent set of photographs should fit into a theory that explains it all (see ).
See also the videos showing pockets -> ->
Some of the geology information on the above site is based on old research (like almost all the Herkimer websites), but the collecting tips are good and the pocket photo is excellent.
A public service project always open to input from the community interested in Herkimer diamonds.
To the right is another photo from Bill and Anne, submitted Sept. 2008. In this shot you can see them sifting through the "black carbon material" (hydrocarbon) and there are lots of clear crystals. This is Middleville, NY (AD).
Web page author - W. David Hoisington, Ph.D.
See also the discusion on pocket mud and wall rock.
To the left is pocket photo from the TCR location, photographed August 2010 (Dr.D.). In this shot you can see hydrocarbon (arrow)and some yellow clay at the left end of the ruler and to the right of the hydrocarbon. This pocket is very close to the surface, note the roots (upper left) and that there is alot of dirt. Early mining days, and back in the 1960's many pockets looked like this. There are still locations in the Herkimer district producing these near surface pockets, but they are getting harder to find.
Often the crystals in these near surface pockets are fractured, sometimes even into separated pieces. Careful digging and one can find all the pieces and reassmble the crystal or crystal group.