Old Theories of How Herkimer Deposits Formed
The best website on "Herkimer Diamonds"
There are many different sites on the internet that promote and offer views about how Herkimer diamonds were formed. Some present information that is simply false. For example saying that Herkimer diamonds formed in volcanic rock (so not true) or that algae created stromatolites (not exactly true) or that Herkimer diamonds were made from dolomite (not true) or that the pockets and crystals are related to magma (a statement made on Wikipedia that was edited 11/12/09) which is misleading.
Most of the information presented about how Herkimer diamonds were formed is based on a particular theory, or idea. What is nice about ideas in geology is that they can be "put to the test". What this means is that the ideas need to match ALL the evidence, both from the field and the lab. Since the mid-1990's new evidence has been appearing every year and often new evidence can make a difference when it comes to geologic theory. The old laboratory evidence of the 1950's and 1960's (which is what some of the internet pubished theories are based upon) needs to be reexamined in the light of improved technology. In addition, currently field work is being done in the Herkimer Mining District in order to gather more information that can be used to support an updated theory for the origin of Herkimer diamonds. Every summer additions are made to the website (see updates link top of this page), providing more new evidence.
There are some "old" theories out there no longer apply, given the new information that has been discovered. The theory that Herkimer diamonds were formed when the original rock was being formed under the ocean (called sygenetic) is no longer a valid theory - regardless of what explanation one attempts to use to describe the processes responsible for making Herkimer diamonds under such conditions. The idea that the black carbon and pocket layers are controlled by "algae mats" that were formed 500 million years ago is just not likely to be true. There is too much evidence to support the theory that Herkimer diamonds formed from migrating fluids enterring into the rock AFTER it was solidified, uplifted, eroded, burried, and fault broken. The discovery of quartz crystal spheres (2009) is added support that oil and Herkimer diamonds are linked together in this post-depositional history. The black carbon material is, most likely, degraded petroleum and thus should be called hydrocarbon (replacing the over applied term anthraxolite).
Some theories suggest a link between stromatolites (or other ancient life), the black carbon and the Herkimer diamonds. But this link needs to be examined closely. It is not likely to be one tied to the original time of the stromatolite formation, but rather to some structural characteristics (increase in holes or porosity) that helped mineral producing fluids move through the rock some time after the stromatolites were consolidated into rock. There is significant evidence for this and not just in the Herkimer mining district, but in other mining districts occuring in Cambrian carbonates as well as other Cambrian stromatolite bearing strata throughout the world.
One of the most important field relationships is the association between black carbon material (called hydrocarbon) and clear crystals. Any theory must explain this and the associated features that are found throughout the Herkimer mining district. The old theories have been inadequate at doing so. The oil migration theory seems to best fit the evidence. See also FAQ page.
New "science" evidence is presented on the science page (see links at the top of the page). There is also new field evidence (see links to Herkimers and minerals top of the page). More new field evidence will be discovered and added to this site. All this new information needs to be considered when constructing a theory that describes how Herkimer diamonds were formed. The new evidence we are seeking to collect, with the help of the public, is described on the "New Research" page.
