Hello Peter
Crystals can be formed from numerous minerals from gypsum, which is extremely soft to carbon (diamond) which is of course the hardest of all known substances. There are I believe more than fifty known forms of mineral crystals Peter, any one of which could be the type located on the site your refer to. An analysis by a professional gemologist could probably determine the mineral which you have found locally, but I doubt very much that you will find any relationship between the source of say quartz crystals or sapphires and diamonds. They are found in very different host rock and exhibit quite different crystal growth structures, cleavage, inclusions, colours and ease of abrasion (hardness).
I believe you have mentioned that you live in Halifax, which is off any craton that I am aware of. That would make finding diamonds very unlikely in your local unless transported by glaciers say from northern Quebec or Labrador where a large craton can be found and Monopros is looking at ground.
Quartz crystal can be found in numerous types of rock but is typically associated with silica intrusion (quartz veins) and vuggy volcanic deposits which might for example produce what are known as Thunder Eggs in the Snake River Valley of western Washington or Mexico. Sapphire can be sourced either from Pegmatite (typically found in granites) and basalt (an ultrabasic rock remotely related to kimberlite). Having said that, a field crew from the University of Western Ontario has found micro-diamonds in a basaltic dyke in the Keewatin Region of the Northwest Territories I believe. There has not to my knowledge been a satisfactory theory proposed to explain that occurrence, but presumably the basalt sampled the mantle at 150km or so and explosively erupted and cooled before the diamonds could be reabsorbed. This defies basalt emplacement theory as I understand it, but obviously the theory does not cover all the bases.
Regardless, some crystals (quartz, gypsum, sapphire, emerald, amethyst, etc.) grow as a result of minerals coming out of solution (water) under the right temperature, chemical and reducing pressure conditions. Diamond uniquely, is believed to form as the result of carbon being subjected to the extreme application of heat and pressure, (not as a dissolved mineral coming out of solution).
There are numerous articles available on the subject and I would recommend that you look up back issues of magazines such as Gems & Minerals. The authors of many of these articles are renowned in their fields and can provide a far more accurate and scientific explanation than I could hope to.
Bottom line Peter is that I very much doubt that digging any deeper will produce kimberlite with diamonds if diggers are finding quartz crystals on surface.
It could be fun to try though.
Regards
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