Cross and Penrose
Rock Collection

Cripple Creek, Colorado

Steven Veatch
James S. Aber

Gold was discovered in the vicinity of what is now Cripple Creek, Colorado in 1890, and mines began regular gold shipments in November 1891. By the spring of 1892, the Cripple Creek gold rush was underway. On a site that was once a remote cattle operation, known as the Broken Box Ranch, Cripple Creek rapidly grew to about 10,000 people by 1894, when Whitman Cross and R.A.F. Penrose, Jr. were there. As part of their geologic investigations of the area, Cross and Penrose created a collection of representative rocks with a particular emphasis on the breccias associated with the Cripple Creek diatreme complex. The diatreme was responsible for the gold telluride deposits in the Cripple Creek mining district, and brecciated rocks are an important host for gold mineralization.

The Cross and Penrose specimens are carefully prepared in a standard size, measuring approximately 7x8 cm each. The specimens are contained in boxes, and a label is in the bottom of each, although many specimens are either not in boxes or missing labels. The labels indicate "Teller County" which was not formed until 1899. Prior to that time, Cripple Creek was located in the western portion of El Paso Country (Colorado Springs). It is most likely the specimens were collected when Cross and Penrose did their field work, September-November 1894. So, the boxes and labels probably were made a few years later.

This collection was recently rediscovered in the Cripple Creek museum by one of us (SV), who cleaned, arranged and photographed the specimens. Following are representative examples. In each photograph the rock specimen is shown next to its box and label.

Specimen A3, granite, Gold Hill, Cripple Creek, Teller County, Colorado.
Specimen C8, andesitic breccia (banded), Moose Mine, Raven Hill, Cripple Creek, Teller County, Colorado.
Specimen C10, banded tuff (probably andesite), Colo. City Mine.
Specimen C34, nepheline syenite, Bull Hill, Cripple Creek, Teller County, Colorado. See next picture for contemporary view of Bull Hill mining operations.
Bull Cliff and Bull Hill from Ironclad Hill, Cripple Creek mining district of Teller County, Colorado. Image taken October 8, 1903. USGS ID RFL00531. Photographer: F.L. Ransome United States Geological Survey Photographic Library.
Specimen C46, augite hornblende andesite, Battle Mountain, Cripple Creek, Teller County, Colorado.
Specimen C50, andesitic breccia, Raven Hill, Cripple Creek, Teller County, Colorado.
Specimen C54, andesite, Battle Mountain, Cripple Creek, Teller County, Colorado.
Specimen C56, rhyolite, Grouse Mountain, Cripple Creek, Teller County, Colorado.
Specimen C59, andesitic breccia, Raven Hill, Cripple Creek, Teller County, Colorado.

Overview of Cripple Creek, Colorado, 1897.
Courtesy of the Cripple Creek District Museum ©.

Return to Penrose and GSA lecture.
GO 521 © J.S. Aber (2003).