New Mexico Mineral Symposium — Abstracts

The Georgetown district is located about 25 miles from Silver City, between the village of Mimbres and the former town of Santa Rita. It is reached by traveling north on Forest Road 73, which joins Highway 152, 2 miles east of Hanover. Today, old dumps and prospect pits are all that mark the site of the mines, and only a cemetery and an empty meadow exist where the town once stood.

The discovery of silver in the Georgetown area dates from the late 1860s. At that time, the area was still partially under the control of the Apache Indians who often raided outlying settlers and travelers. Little development of the silver deposit occurred until about 1873, and by 1875, the camp was booming. Several substantial underground mines were developed and operated by a number of companies, the largest of which was the Mimbres Consolidated Mining Company. Notable mines included the Naiad Queen, Commercial, McNulty, Satisfaction, and McGregor. Most of the ores were sent to mills and smelters 3 miles to the east on the Mimbres River where there is a reliable source of water. The decline of silver prices in 1892 was the beginning of the end for the mines, and production swiftly declined. At the turn of the century, F. A. Jones reported that production from the district amounted to $3.5 million dollars, and subsequent writers have placed the total loser to $10 million. Since then, several lessors continued to work the old stopes with limited success but never on a large scale. An attempt to recover silver from old dumps through heap leaching was made in the 1980s without success. Today, the recent leaching operation has been reclaimed, and all the major mine openings have caved or been closed to prevent entry.

The silver and lead ores of the district are found within the Ordovician Fusselman limestone that lies directly beneath the Devonian Percha Shale. The shale forms an impervious barrier to rising mineralized solutions. Granodiorite porphyry dikes are found in the mines that may be related to the intrusion of the adjacent Santa Rita stock. Orebodies were developed along fracture zones, as replacement of the limestone adjacent to the contact between the two formations and along the dikes. Miners explored for ore by drifting along the contact looking for mineralization often disclosed by the abundant deposits of bright orange descloizite along fractures. The original sulfide mineralization has been almost completely replaced by a colorful suite of oxide minerals.

The district has been of interest to mineral collectors for many years for the fine specimens of vanadanite and descloizite that occur in the mines. In April 1889 the noted mineral dealer George English visited the mines and was offering descloizite as "extra fine specimens, averaging lx1 inches, for 10 to 25 cents; 2x3 inches, 50 cents to $2.50; 3x4 inches, $1.00 to $3.50, shelf and museum specimens, $3.50 to $15.00" in his 1897 catalog.

The species list from the district is not large and is largely derived from the oxidation of primary ores dominated by galena. Most of these minerals can still be collected as micromineral specimens on the dumps by the patient and determined collector.

• argentite—reported
• aurichalcite—uncommon
• bromargyrite—sparse
• calcite—abundant
• cerussite—common
• chlorargyrite—reported
• descloizite—abundant
• galena—uncommon
• hemimorphite—common
• iodargyrite—reported
• malachite—rare
• plattnerite—rare
• "pyrolusite"—common
• quartz—common
• silver—reported
• vanadanite—common
• willemite—•uncommon
• wulfenite—uncommon