In the early and mid 1970’s I spent several months working on the uranium potential of the Denver Basin and, in particular, the area east and southeast of Colorado Springs and Trinidad. We were evaluating mostly Lower Cretaceous rocks but spent some time checking surface and sub-surface anomalies based on areal and ground water sampling programs. Surface rocks in much of this area consist of Upper Cretaceous shales containing multiple horizons with large concretions.

On a late afternoon in 1972, returning to our base of operations in La Junta from the area near Timpas, we stopped to check a shale unit along the highway and found several promising concretions. We excavated one, about 4′ in diameter, and found what may have been the first reported clear barite in what was later called the “La Junta” barite area. These barites are often water-clear and display a variety habits some of which are remeniscent of those found in concretions near Grand Junction.

The specimen pictured was displayed at the Denver Gem and Mineral show in, I believe, 1976 in a Self-Collected Minerals case. The blocky crystal is about 2.3 cm on an edge. It generated a bit of interest and the location was given to several people, including Don Knowles who reported little success after at least one trip to the area. Some years later I received an inquiry from Dan Kyle about the location and sent maps of the area to him. As most collectors in the Denver area know, Dan has found some very fine specimens there.

While much has been said about the clear barites there are two additional locations that I have always wanted to re-visit. One, not far from the original barite discovery, was near a well where we collected a water sample. Weathered concretions on the surface nearby contained lovely rosettes of white, flattened calcite rhombs up to 3 inches across displayed on a matrix coated with orange-brown lichens. Another, some miles to the east, was a somewhat obscure zone of smaller concretions, up to about 2.5-3 feet in size, with tabular blue to blue-gray and yellow zoned barites up to 2 inches on a calcite-crystal matrix. We spent less than 20 minutes walking contour on this concretion zone and found one weathered open, with the crystals described above and several others that looked promising but we did no digging.

In the mid-1970’s I spent some time working in SW Colorado in the La Plata Mountains near Durango. This area has produced significant gold (the Bessie G mine, for example, was active at that time) and has been investigated for its porphyry copper potential and uranium as well.

The Tomahawk Mine and basin are located above timberline in the western part of the complex. Rocks in the area include a variety of intrusives and metamorphosed sediments that form the high ridges and cliffs around the head of Tomahawk Creek. The Tomahawk mine produced gold in the last century. At the time I worked in the area there was still a very thin, rich vein containing visible gold accessible (if you were a skilled rock climber) on the cliff face at the creek near the mine ruins.

Above: Tomahawk Basin seen from high ridge to SE.

Below: Tomahawk Mine structures in 1975.

What passed for a road ended a few hundred yards west of the mine at a drill site located near a small intrusive complex. Talus from the high cliffs to the south of this intrusive contained scattered vugs that were mineralized with epidote, quartz, K-feldspar and rare fluorite. The fluorite crystals were simple octahedrons of a rich violet color. Their maximum size was about 2 mm.

I have always thought that it would be worthwhile to investigate the area for the source of the fluorite. Perhaps there are larger cavities and better crystals in the larger talus or lower cliff faces a few hundred feet up and to the south of the intrusive. Are there any of you energetic young collectors interested?