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 and slightly younger granites. Throughout most of its length, the crest of the range is capped by a thick sequence of tilted Pennsylvanian-Permian redbeds. These beautiful rust-colored sediments take on a distinctive rosy red hue during certain times of the day. To the devout Spaniards, the range became known as the Sangre de Cristos ("Blood of Christ"). The eastern slopes of the Sangres are also made up of these tilted Pennsylvanian-Permian sediments. On the western side of the Sangres, Precambrian granite 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 forms the crest of the range. Examples include the Blanca Peak area, just west of La Veta Pass, and the Culebra Peak area, near the New Mexico border.
The Sangre de Cristo Mountains were pushed up along a group 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 Culebra Range makes up the bulk of the Sangre de Cristo chain just north of the New Mexico border. The Culebras are situated near the contact between ancient Precambrian country rock and younger Pennsylvanian sediments. Most of the peaks in the Culebra Range are made up of this Precambrian granite. Only on the eastern side of the range do younger Pennsylvanian-Permian sediments crop out.
North of the Culebra Range, the Sangre de Cristo chain gradually dwindles in elevation until North La Veta Pass (9413 feet) breaches the range near Mount Maestas. The Sangres bend westward from the pass, then suddenly rise up to form the Blanca Peak group of 14'ers. The Sangres continue northwestward from Blanca Peak, first rising up to form the 14,000-foot Crestone Range, then gradually diminishing until Poncha Pass (the "mild" pass) is encountered, roughly 100 miles northwest of the Culebras.
Immediately north of the Culebra Range, the Sangre de Cristo mountain chain is made up of ancient Precambrian metamorphic basement rock along its western flank and younger Pennsylvanian-Permian sediments along its eastern flank. The crest of the range is sometimes overlain by the older metamorphics, sometimes by the younger sediments.
In the Spanish Peaks area, much younger Tertiary intrusives and related volcanic rocks crop out. The peaks themselves and the many dikes radiating from them are the remnants of this mid-Tertiary intrusive activity.
Very few mining districts occur in the southern portion of the Sangre de Cristo Mountains of Colorado. The only gold-producing districts south of Blanca Peak are in the Spanish Peaks area and in the Grayback Mountain/Iron Mountain region. The Spanish Peaks are home to three small mining districts: the La Veta District, the Spanish Peaks District, and the Wayatoya Creek District. The first was founded on lode gold production while the last two were focused on placer gold production. The La Veta District contained only small veins of gold-bearing sulfides emplaced within a Tertiary intrusion.
The Grayback District is located just west of North La Veta Pass, near the town of Russell. This small district contained lode deposits of gold-bearing pyrite plus several placer deposits located below the veins. The best placers were in Spanish Gulch, Grayback Gulch, Giant Gulch, and Placer Creek.
Like the Sharron party back in 1858, modern-day prospectors face a daunting challenge in their search for the Lost White Cement Mine. First of all, the area of interest is incredibly vast. Stretching from the New Mexico border northward to La Veta Pass, the area encompasses over 400 square miles of rugged mountains and steep canyons. Secondly, the area contains only sparse mineralization. Only two small gold-producing regions occur south of Blanca Peak: the Grayback Mountain/Iron Mountain area near La Veta Pass and West Spanish Peak. Neither of the two regions was especially rich. Thirdly, the gold-bearing cement formation is like none of the conventional ore bodies described in the literature. Unless one examines it closely, the cement-like ore body is probably quite nondescript and unremarkable in appearance. It certainly wouldn't look like rich ore. A prospector would be apt to walk right by it without even noticing it.
Prospectors should probably concentrate on the areas adjacent to Precambrian and Tertiary igneous rocks. The link between hypogene (or primary) ore deposits and magmatic activity is irrefutable. In mining districts throughout the world, most hypogene mineral deposits are derived from a magma source. But is the cement ledge truly igneous or could it be sedimentary in origin? Unfortunately, a really detailed description of the ore itself is lacking. Is the gold-bearing cement ledge a conventional vein of white, corroded, aphanitic "sugar quartz" that superficially looks like cement or is it a clastic sedimentary formation containing ancient alluvial gold mixed with quartz? In either case, prospectors must be aware of the unique nature and appearance of the white "cement" ledge if they choose to seek it.
So, where does one start in their search for the Lost White Cement Mine? Prospectors may want to focus on the Culebra Range, just north of the New Mexico border. The Culebras contain large bodies of Precambrian granite emplaced within older metamorphic country rock. These ancient metamorphic rocks may contain veins of gold-bearing ore. In 1892, a man named Ashton B. Teeples claimed to have discovered a fabulously rich placer deposit of gold in a small lake near Whiskey Pass, located at the north end of the Culebras. Could the lost cement ledge be the source of Teeples' placer gold?