Tennessee Field Diamonds

A treasure 485 million years in the


Weathering of carbonate bedrock

Crystals freed from carbonate bedrock now in residual clay.

Quartz crystals in clay residuum.  Most crystals in the Knox dolomites are found on the surface or in residuum after decomposition of the bedrock

Unusual matrix specimen from Douglas Dam, again found on the surface after being incorporated in the clay residuum.

Typical Douglas Dam crystals with black carbonaceous inclusions.

Large blocky crystals.  The broken surfaces show re-growth of quartz such that the broken crystal, upper right, must now be held together with poster putty.

Thin prismatic reverse-scepter.  This crystal shows long prismatic quartz deposited over stubby prismatic quartz, and suggests a more complex paragenesis, as the most commonly seen order of formation is prismatic followed by bipyramidal quartz.

Typical black inclusion crystal.

Specimen of elongate quartz showing oriented black inclusions. 

Crystal above, close up. 

The black inclusions appear to be hollow, gas filled, coated with a blackish-brown crust inside.

Parallel chain type morphology.

Large bipyramidal crystal from Douglas Dam.

Large Douglas Dam Crystal

Another large Douglas Dam crystal

One of the largest specimens from Douglas Dam that still shows good morphology.

Fincher Farm  area

(Locality 12)

Kingsport Formation,
Knox Group dolomites.

This is one of a number of nearby areas in Greene County.

Fincher Farm shows a great variety of morphologies.  The locality has become picked-over since being listed on the Internet as a geocache site.

Well-displayed two-stage quartz scepter growth.

Another example of scepter growth, prismatic quartz followed by bipyramidal quartz.

Example of bipyramidal and skeletal growth.

Multiple parallel bipyramidal crystals.

Large chain-crystal  specimen.

Irregularly developed chain crystals.

Large bipyramidal complex crystal

An even larger bipyramidal complex crystal.

This specimen shows two growth stages separated by corrosion or a dusting of fine fragments.

Another such example.

The “hind ends” of the two specimens showing overgrowth morphology.

Low-power photomicrograph.  The larger sparkly fragments are small randomly-oriented quartz crystals.

Another overgrowth specimen.

Bipyramidal over “dusted” prismatic quartz.

Assymetrical growth indicative of currents during later development, coming from the left as the specimens are displayed. The "arm" on the larger specimen is crystallographically continuous with the rest of the crystal.


Crystals from a small deposit near
I-81 Exit 8
(locality 10)

Jefferson County, TN