New Mexico Mineral Symposium — Abstracts

On the western side of Pikes Peak in Colorado, at a site that was once a remote cattle operation known as the Broken Box Ranch, a cowboy named Bob Womack discovered gold in 1891. A gold rush was soon underway: The Cripple Creek mining district was established while local mines began regular gold shipments. The gold mining district, known as "The World's Greatest Gold Camp," grew from a few prospectors after Womack's initial discovery to a peak population of more than 60,000 people. By 1900 the district had more than 500 active mines.

Since 1891 more than 23 million ounces of gold have been produced—making Cripple Creek the third largest gold mining district in the United States and one of the largest gold-telluride districts in the world.

The gold deposits occur within a 7-mi² Oligocene (- 30 Ma) alkaline diatreme complex emplaced at the junction of four Precambrian units along the western margin of the Pikes Peak batholith. The complex consists of an upward-flaring volcanic neck filled by heterolithic volcanic breccia with evidence for significant vertical transport during magmatism such as carbonized wood more than 3,000 ft below the current surface. A complex series of alkaline intrusions are found within the diatreme that form composite flows, dikes, sills, laccoliths, and dome-shaped features intruding diatremal breccias and the surrounding Precambrian rocks.

A process of mineralization, spanning about 2 m.y., closely followed the emplacement of the volcanic complex, with most of the gold localized along major structural zones (north-northwest and northeast) within the volcanic complex. The orebodies occur as (1) deposits of rich, narrow gold-telluride veins with quartz, pyrite, rutile, and fluorite and (2) deposits of low-grade, disseminated, microcrystalline, native gold attached to pyrite. Most of the gold mined in the early days of the district came from the high-grade gold-telluride veins.

Cripple Creek had grown rapidly to about 10,000 people by 1894 when the United States Geological Survey (USGS) sent Whitman Cross and Richard A. F. Penrose, Jr., to conduct field work and to prepare a report on the geology and mining of the Cripple Creek goldfields. Richard Penrose's younger brother Spencer was already at the mining camp.

Whitman Cross (1854-1949) was a prominent field geologist who had done most of his field work in the Colorado Rockies where he mapped more than 9,842 km² (3,800 mi²) of southwestern and central Colorado. Much of his mapping was in extremely rugged country that required travel on foot, horseback, and pack train. His major field areas were related to new mining districts and included Cripple Creek, Crested Butte, Telluride, Rico, and the San Juan Mountains. His field parties were recognized as excellent training for young geologists.

Richard Alexander Fullerton Penrose, Jr. (1863-1931), was a mining geologist and an investor who had accumulated great wealth through shrewd investments in mining stocks. He received a Ph.D. degree at the young age of 23. He worked in Texas, Arkansas, Arizona, and Colorado, where he pursued mapping assignments with the USGS and acted as a private consultant.

As part of their geologic investigations of the Cripple Creek mining district, Cross and Penrose made a collection of representative rocks (which still exists today in the Cripple Creek Museum) in 1894 with a particular emphasis on the breccias associated with the Cripple Creek diatreme complex. The breccias are an important host for gold mineralization in the district.

The Cross and Penrose specimens were carefully prepared in a standard size, measuring approximately 7 x 8 cm each. The specimens were stored in boxes with a label in the bottom of each. Today many of the specimens are either not in boxes or are missing labels. The Cross and Penrose rock collection was recently rediscovered in the Cripple Creek Museum by S. W. Veatch who cleaned, arranged, and photographed the specimens. This collection represented the petrology of the mining district and became the foundation of the USGS report Cross and Penrose made on the Cripple Creek mining district in 1895. This report was important for two reasons: (1) this was the first scientific report on the district and (2) mine owners used this report to raise capital and expand their mines. Spencer Penrose's mine, the C.O.D., was featured in the report and soon sold for $250,000—the largest amount ever paid for mining property at that time in the district.

Not only was this rock collection the basis of the report and the geologic mapping of the district, but it also brought together in Cripple Creek the principal investors of what would become the Utah Copper Company and the inventor of the technique that made the processing of low-grade copper ore profitable—Daniel Jackling (1869-1956). While working in a Cripple Creek mill from 1894 to 1895, Jackling developed relationships with the Penrose brothers and others who would later provide funds for the Utah Copper Company.

Daniel Jackling had been working on new mining and milling methods that would transform mining. His new process included mining with large open pits, using huge mechanical shovels, and having steam locomotives haul ore cars to the mill. A number of mining magnates had turned down Jackling's proposal to mine low-grade copper ore; the problem was that a great amount of capital was needed to get the project going. Spencer Penrose had money to invest and began to listen in earnest to Daniel Jackling. Richard Penrose, who also had the funds to invest, carefully evaluated the project and thought it would work. Richard Penrose also knew that with the dawn of the age of electricity there would be enormous demand for copper.

In 1903 Richard Penrose co-founded the Utah Copper Company, the predecessor of Kennecott Copper, in order to develop the rich Bingham Canyon copper deposit in Utah. Although no one in mining circles believed the process would be profitable, the project at Bingham Canyon, called "Jackling's Folly" by its critics, was started. The process turned out to be profitable, and over time the Bingham Canyon ore values became greater than the worth of the Comstock lode, the California and Klondike gold rushes combined, and eventually made the Utah mining operation the richest hole on Earth.

Richard Penrose's interest in the Utah Copper Company brought him considerable wealth. Daniel Jackling also benefited financially from his involvement with the Utah Copper Corporation and was a millionaire by his fortieth birthday. Spencer Penrose, who profited from the Cross and Penrose rock collection and from the Utah Copper Company, established the El Pomar Foundation upon his death to benefit people of the Pikes Peak region and Colorado.

Because of shrewd investing and his interest in the Utah Copper Company, Richard Penrose was able to make a large fortune. At his death (1931), few suspected his true wealth or knew of his will. Penrose had no children or other heirs who could benefit. Most of his estate was equally divided between two scientific organizations, the American Philosophical Society of Philadelphia and the Geological Society of America (GSA).

GSA was founded in 1888 for the purpose of "the promotion of the science of geology by the issuance of scholarly publications, the holding of meetings, the provision of assistance to research, and other appropriate means." The organization experienced steady but unremarkable growth to around 600 members by 1930. The single most important event since its founding occurred in 1931, when GSA inherited an endowment of nearly $4 million from the estate of R. A. F. Penrose, Jr.

The Penrose legacy has benefited GSA greatly. His endowment transformed a small unremarkable, scientific society into a world leader in geologic science. Membership has grown to more than 10,000 fellows, professionals, and students. GSA is without question among the largest and most productive geological organizations today. Its success mirrors the diverse and dynamic nature of geology as a key component in global environmental and resource issues that face modem society.

×