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The "Baby Floater" Stage - The Seed Crystal Theory for
making Herkimer diamonds
Although not discussed much, the pockets which contain Herkimer diamonds often contain many very tiny Herkimer diamonds. These frequently can be found to apparently have no growth contact points. It seems they were "floating" in some fluid when they crystalized. These tiny Herkimer diamonds have been found as inclusions "floating" within larger Herkimer diamonds and also "floating" within fluid inclusions as detached crystals. They can also be found as a unique looking druze coating, here termed "baby floater druze". These baby crystals probably acted as "seed crystals" for the larger Herkimer diamonds. This is the "Seed Crystal Theory" of Herkimer diamond formation.
W. David Hoisington, Ph.D.
The easiet observable form of the "baby floater" stage is as tiny inclusions of Herkimer diamonds. The larger crystal on the right is only 7 mm tip-to-tip. The "baby floater" can be clearly seen inside and outside the larger crystal.
The other observable form of the "baby floater" stage is as loose tiny crystals. The photo is of washed pocket mud, look around and you will see all the tiny crystals. Also see the top photo of loose crystals without rock fragments. Note the scale, and that these are called "baby floater" because of how tiny they are. Litterally hundreds of these tiny crystals can be found in a pocket along with larger collectable Herkimer diamonds.
Variations of the Baby Floater Inclusions
The Baby Floater Druze
The other observable form of the "baby floater" stage is as "manifestations" (which are presumed to be hollow, a determination difficult with an unaided eye). These are ghost imprints of tiny crystals inside a Herkimer diamond. Note in the above photo you can see the edged faces of a small Herkimer inside the larger clear crystal, but you can also a smaller crystal sticking out the side on the left. This specimen ifs from AD, photo is donated by Mike Eggleston(2012). It may be that this type of inclusion is different from the fluid inclusions that have crude edges and faces - see the inclusions page.
One of the most common form of the "baby floater" stage is as fragments. In many of the crystals that come from hydrocarbon pockets it is common to see these as inclusions. Note above the jagged edges and the incomplete crystal form of the inclusions.
There are more of these fragment type baby floater inclusions shown in the photo below. You can tell that you are looking into a larger crystal because you can see a face edge on the right and face striations running down the center.
On the left, this specimen ( 9 cm across) from Fonda, NY (DA) that shows a different type of druze. In this specimen larger Herkimer diamonds sit on top of this special druze (blue arrow). It is here named "baby floater druze" because it appears to be a coating of microsopic Herkimer diamonds. A close up photo is on the right.
To the right is a close up of the specimen on the left and shows some key features of the baby floater druze (red arrow). First, the crystals are very tiny. The photo is only 2 mm across. Secondly, the druze has no "rind contact", like in other druze (see the druze page) and the crystals are scattered about and not in parallel growth. Finally, the exposed rock is very eroded (probably a hydrothermal effect connected to the baby floater event). An important point to consider - if this was the wall rock of larger pockets it would be quite unstable. Given this to be the case, then much of the wall rock would show collapse and be found with the mud at the bottom. This is often where many baby crystals are found (see photo of pocket mud).
On the right is another photo illustrating the very tiny size of some of the baby floater druze. Here it is coating the earlier pyramidal druze, which can be seen as pointed peaks (below the blue arrow the peak is only 1 mm wide at the base). One way of getting a sense of how small these are is to sprinkle some salt into your hand. Those salt grains are about the same size as these tiny "seed crystals".
Like with other examples of the baby floater druze, there is alteration of the rock, an etching of the previous druze, and the baby floater crystals are not in any parallel growth pattern like other druze but instead are just sprinkled about.
The microscope photo on the left shows a light coating of microscopic Herkimer Diamond like crystals on an "eroded" matrix. The blocky crystals are dolomite. From Herkimer Diamond Mine, Middleville, NY. Photo, Dr. C. The largest dolomite is only 2 mm across and has more of a peach color in natural light.
This rock, called pocket wall rock, seems to be fairly common for Herkimer diamond pockets from this mine.
The Baby Floater Episode - Conclusions
Below is a citrine clear crystal, 7 cm long, that has many "baby floater" contacts showing a number of different features. Close up is on the right. Fonda, NY (DA), a unique champange crystal pocket, Mike Hoisington, 1972. Photo by DrC. 2008.
The above evidence suggests that the baby floater event came after the early druze and before the major Herkimer diamond event. It also appears that the baby floater event had a strong effect on the host rock, creating alteration features that look like what would happen if heated corrosive fluids entered the rock. But perhaps the most significant impact of the baby floater event was its role in providing "seed crystals" from which the larger Herkimer could grow. This is called the seed crystal theory for Herkimer diamond formation.
The seed crystal theory is pretty simple. It proposes that there were very tiny Herkimer diamonds floating, in solution, in the fluids that eventually helped to make Herkimer diamonds. These tiny Herkimers diamonds acted as "seeds" for the growth of larger crystals. It was probably a critical part of how Herkimer diamonds were formed.
A closeup, showing the tabular fragments, can be seen on the inclusions page.