from Colorado, USA
What is the Sloan Kimberlite?
The Sloan Kimberlite group consists of 6 known kimberlite bodies within the State Line district of northern Colorado. At least 4 of the intrusive bodies are diamond-bearing. Kimberlites are near-surface igneous rocks derived from a magma originating in the Earths’ upper mantle. They are known for their diamond-bearing capabilities… think South Africa and the Northwest Territories of Canada. The Sloan kimberlite contains abundant secondary/alteration minerals, mostly importantly serpentine minerals.
Under the Microscope
We choose to show off the serpentine alteration minerals in our Fierce design. The serpentine in this image replaced a rounded grain of what once was a mineral plucked from elsewhere (xenocryst) or a primary mineral from the magma (phenocryst). We think it’s likely a replacement of olivine. Now all you see in transmitted, cross-polarized light is the strong contrast of light and dark in large serpentine fibers and an almost vintage greyscale in-between from smaller fibrous grains.
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