colored gemstones

Gemstone and Mineral Mines of San Diego County

rhodalite

Mesa Grande Mining District

Setting:

The Mesa Grande mine is located near the center of the N/2 Sec 20, T11S, R2E, SBM, nearly 2.5 miles (4 km) northwest of Mesa Grande on the steep east slope of Gem Hill within the boundaries of the DeForest Ranch property, located immediately adjacent to the Angel Ranch property. Livestock raising activities have traditionally dominated the use of surrounding lands, and although conflicts between ranchers and miners occasionally erupt over mineral rights, local ranch hands have played an important part in the development of the gemstone resources in the area.

Geology:

The geology of the Mesa Grande mine consists of a local series of three continuous pegmatite dikes averaging 2 to 4 feet in thickness, enclosed within a well-defined gabbroic micropluton. These dikes follow a general north to northwest strike and display an average dip of between 20 and 35 degrees west to southwest. These vein-like bodies are clearly exposed and traceable along the available surface exposure and should be considered prominent southern extensions of the productive Himalaya dike system. The gem-bearing portions of the deposit are located within the central portions of these dikes, characterized as quartz-subhedral perthite pegmatite forming distinctly localized areas of abnormally enlarged crystal structure.

History:

The Mesa Grande mine workings were reported to have originally opened sometime between 1903 and 1904, by the Mesa Grande Tourmaline and Gem Company. The officers of the company were: President, Frank A. Seabert, whom spent a large portion of his time at the property; Vice-President, Horace Wilson, a well known business man of Los Angeles; Superintendent, C. O. McCarroll, pioneering California gemologist; Secretary, H. E. Felkenson of Southwestern Securities Company; and Los Angeles Banker, Frank A Liddell. The mine yielded a modest amount of pink and purple tourmaline, beryl (aquamarine and goshenite), and quartz (white and smoky). At least 1100 carats of tourmaline gems were reported to have been cut and sold. The principal development during this period was a cut 60 feet long, 15 to 40 feet wide, and 25 feet deep. From this main cut was driven an adit which extended 80 feet underground into the mountain, cutting through the first two dikes, at which point an appended drift followed the southernmost pegmatite to the northwest for nearly 180 feet. Other cuts and minor adits were driven along the surface outcroppings of the three main dikes, extending down dip no greater than 20 feet. Work on the property by the company had ceased around 1910.

Himalaya Mine

The Himalaya Mine is famous for the beautiful elbaite, rubellite and verdelite tourmaline gemstones and associated combinations which have been mined there for many years. Other minerals found at the mine include spessartite garnet, bladed albite clusters, etched feldspar crystals, stibiotantalite,topaz, morganite beryl, smoky quartz, clear quartz, lepidolite balls and clusters, and combinations of these minerals.