Tennessee Field Diamonds

A treasure 485 million years in the


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

Jefferson County, TN

The area is a roadside excavation for fill dirt.  Quartz crystals were first noticed here in breccia vugs in a dolomite exposure.  This image shows thin almost needle like quartz crystals and two larger ones.

Later the residual clays were searched and some concentrations of quartz crystals located.  These are some of the more typical crystals.

An elongated prism found on the surface.

Unusual compound bipyramidal crystal.

Another view showing the two parallel crystals in contact with each other.

Large complex form, largely bipyramidal.

Another large complex bipyramidal form.

Complex or multiple bipyramidal specimen.  The separate sections were only weakly connected, and had to be glued together after being collected.

Multiple “fantasy castle” crystal.

Mosheim Anticline

(locality 11)

Red soil exposed in recent excavation

This area of red soils in a shallow excavation was discovered by Mike Streeter of the North Carolina Survey

Parallel and “bow-tie” growth forms.

Parallel and “bow-tie” growth forms.  These are the earlier growth forms at this location.

Parallel and “bow-tie” growth forms.  These are the earlier growth forms at this location.

Elongated prisms.

Clear prismatic crystal.

Compound crystal – compound prismatic crystal joined to a parallel bypyramidal crystal

Another view.

Large crystal picked up by Brett Shaffer.

Specimen showing progression from a rough elongate crystal through stubby prismatic forms and finally to a large crystal of bipyramidal morphology.

The other side, showing a large fluid inclusion with bubble.  The inclusion also contains a tiny separate crystal that moves around when it is tipped or shaken.

Photomicrograph of loose movable floater (center).


Sevier Shale

Quartz crystals in the Sevier Shale show that at least some quartz deposition took place
during or after the Alleghenian

The other geologic environment where I’ve found quartz crystals is the Sevier Shale.  Here, they are also found in open space within vugs, although again, it is possible there may have been some soluble component present when they formed.  Rock salt may have been a matrix, and again, anhydrite is common in rocks at depth.  It occurs in the zinc mines for example.  But again, if it was there, you would still see it in the inclusions.

The crystals are much simpler in most places.  There is little or no evidence for more than one stage of growth, but there are some multiple parallel crystals.  The Sevier Shale was deposited after the post-Knox unconformity, and all open space is the result of deformation (faulting and folding) that took place during the Alleghanian orogenic episode.