Hercules walked off with a powerful stride and soon reached the end of all land in the west.
—d'Aulaire, Mortal Descendants of Zeus
Setting:
The Hercules mine is about 4.5 miles east-northeast of Ramona, encompassing the southern slope of a hill with an elevation of 2480 feet from which the coast of the Pacific Ocean is visible. The south side of the hill slopes steeply towards the southwest, following the general dip of the pegmatite intrusions which outcrop along the top and just north of the hill's ridge. The location is mainly in the S/2 SE/4 NE/4 Sec. 8, T. 13S, R. 3E, SBM. The site borders the Little Three property on the north.
The Hercules pegmatite is north of the Little Three dike, and is primarily known for its production of bright orange spessertine. The pegmatite has been primarily developed where it dips down onto the Little Three mine property.
Geology:
The area of the Hercules mine lies in the mid-southern portion of the Peninsular Range province. The most abundant rocks found in this area are the many granitic plutons which constitute the southern California batholith. Other rocks found in the area are meta-sedimentary and meta volcanic rocks the antedate the batholith and form a wide spread but generally minor part of the terrain. The length of time between the injections of the gabbro and that of the final granite in the batholith is believed to have been approximately 10 million years. The batholith is made up of many separate injections. The succession of intrusions is from gabbro to tonalite, to granodiorite, and finally granite.
Discrete pegmatite bodies occur throughout the batholith and in some cases with the older meta-sedimentary and meta-volcanic rocks. The geology of the Hercules mine is comprised of partial alluvium overlying a bed rock consisting of large solid quartz monzonite and gabbroic xenoliths in decomposed quartz monzonite, containing complex pegmatite intrusions.
The granitic pegmatite intrusions found at the Hercules mine produce a variety of solid solution series minerals, occurring in both gem and specimen quality, usually in kaolinite filled miarolitic cavities (pockets). Minerals found include: Beryl; Clinozoisite; Garnet; Lepidolite; Muscovite; Microcline, Cleavelandite; Quartz; Stibiotantalite; and Elbaite. These pegmatites appear as a localized swarm in which the individual dikes run parallel to each other. The Hercules dike strikes northwestward and dips about 45 degrees south, and averages 2-3 feet in thickness. The ledge is traceable for over 1000 feet along strike.
History:
The Hercules was originally located in August of 1903 by A. W. Pray, S. G. Ingle, and Harry Titus of Ramona, as 2 end-to-end north-northwest trending lode mining claims. Most of the early development work was done by Pray.
Between 1904 and 1938, development consisted of a 200 foot tunnel, and a 50 foot tunnel on the vein. These working were said to have produced about 15 pounds of gem quality spessartite and 1/2 pound of green beryl. When cut, the spessartine gems ranged from about 1 to 6 carats. By 1939, the claim was owned by W. H. Davis of Pasadena, who reported the mine to be idle.
In 1954, Robert B. Winstead and George Converse of Ramona relocated a single north-trending claim. Workings were described at that time as several shallow open cuts and a 50 foot adit driven northwestward from the south border of the claim. (include John Sinkankas work)
From mid-1957 to the early 1990's, the Spaulding family recovered many kilos of spessartine from the Hercules dike. (add Sinkankas; Gray developments)
In December 1995, the San Diego Mining Company began probing inside an old brush covered and partially caved adit which revealed the continuation of a large gem pocket that had been discovered and worked by hand many decades earlier. The single gem pocket produced nearly two kilograms of mixed grade spessartine garnet, approximately 40 grams being of facetable quality material, along with large amounts of associated minerals such as smoky and citrine quartz, black tourmaline, cleavelandite, microcline, and muscovite.
References:
Kunz, G. F. (1905) Gems, jeweler's materials, and ornamental stones of California. California State Mining Bureau bulletin 37, pages 49, 52-53, 140-149.
Simpson, D. R. (1965) Geology of the central part of the Ramona pegmatite district, San Diego County, California. California Division of Mines and Geology, Special Report 86: p. 3-23.
Rynerson, F. J. (1967) Exploring and mining for Gems and Gold in the West. Happy Camp, California: Naturegraph Publishers, Inc., 204 pages.
Stern, L. A., Brown, G. E. Jr., Bird, D. K., Jahns, R. H., Foord, E. E., Shigley, J. E., and Spaulding, L. B. Jr. (1986). Mineralogy and geochemical evolution of the Little Three pegmatite-aplite layered intrusive; Ramona, CA. American Mineralogist, 62: 966-978.
Sinkankas, J. (1997) Gemstones of North America. Tucson, Arizona: Geoscience Press Inc., 526 pages.
Tucker, W. B., Reed, C. H. 1939. Los Angeles Field District - Mineral Resources of San Diego County. California Journal of Mines and Geology, quarterly chapter of State Mineralogist's Report 35; January: p. 37-40, Illus., maps.
Weber, F. H. 1963. Geology and mineral resources of San Diego County, California. California Division of Mines and Geology, County Report 3: p. 104; illus., maps.
Rocks & Minerals: 63: 138.
|
|
|
Map Reference: 33°3'31"N , 116°47'32"W
Important Disclaimer: This locality information is for reference purposes only. You should never attempt to
visit any sites listed in mindat.org without first ensuring that you have the permission of the land and/or mineral rights holders
for access and that you are aware of all safety precautions necessary.
Switch between Map and Globe
|
