COLORADO

The Lost Mine of Blanca Peak

GEOLOGY OF THE AREA


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The Sangre de Cristo Mountains of south-central Colorado are an uplifted, block-faulted chain of rugged peaks consisting of ancient Precambrian basement rock and younger Pennsylvanian-Permian sediments. The Precambrian rocks include truly ancient metamorphic country rock intruded by slightly younger granites. Throughout most of its length, the crest of the range is capped by a thick sequence of tilted Pennsylvanian-Permian red beds. These beautiful maroon-colored sediments take on a distinctive rosy hue during certain times of the day, hence the name Sangre de Cristo ("Blood of Christ"). The eastern flanks of the Sangres are also made up of these tilted Pennsylvanian-Permian sediments. On the western side of the Sangres, Precambrian crystalline rock is exposed along the base of the range. Higher up the slopes, younger Paleozoic sediments rest unconformably upon the ancient Precambrian basement rock. In some sections of the Sangre de Cristos, Precambrian granite makes up the crest of the range. Examples include the Culebra Peak area, the Blanca Peak area, and the Crestone Range.

The Sangre de Cristo Mountains were pushed up along a set of high-angle thrust faults that pretty much run the length of the chain. Faulting commenced during Laramide times, but sporadic movement occurred throughout the Tertiary Period.

The Blanca Peak complex consists of a large Precambrian granitic intrusion bounded on the east by a belt of Precambrian metamorphic country rock and younger Pennsylvanian-Permian sediments. The contact between these rocks and the granites of Blanca Peak lies just east of the Ute Creek drainage, near the Grayback District.

Very few mining districts occur in the southern portion of the Sangre de Cristo Mountains of Colorado. In the Blanca Peak area, only two relatively small mining districts are known, each founded on similar ore deposits. Both the Grayback District (located just east of Mount Lindsey) and the Blanca District (located on the western side of the peak) contained small gold-bearing pyrite veins emplaced within Precambrian metavolcanics and Paleozoic limestones.

PROSPECTING POTENTIAL

The extremely rugged, heavily forested slopes of Blanca Peak offer some unique challenges to the modern-day prospector. Besides the difficulty of operating in such rugged country, mineralized zones turn out to be few and far between. And when they do occur, they are only moderately rich at best. The Sangre de Cristos contain no substantial mining districts and never have.

The Blanca Peak complex does have two small gold-producing districts in the immediate vicinity. The Grayback District lies just east of the complex while the Blanca District is located on the peak itself. Both produced similar ores consisting of gold-bearing pyrite veins.

The Precambrian crystalline rocks of the Sangre de Cristo Mountains are home to several mineralized zones, each of which lies on the western side of the range. These include the gold-producing districts near Crestone, Spanish City, Cottonwood, Duncan, Liberty, Camp Commodore, and Russell. All produced ores consisting of gold-bearing sulfides.

Prospectors may want to concentrate on the rugged slopes of Blanca Peak, beginning on the western side near Holbrook Creek and continuing southward all the way around the mountain, then eastward toward the Grayback District. It is a vast area to prospect. A metal-detector may prove useful in the search for gold-bearing "float" on the mountainside.


 

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