Little Three Mine (Little 3 mine), Ramona, Ramona District, San Diego Co., California, USA
|Latitude & Longitude (WGS84):||33° 3' 26'' North , 116° 47' 35'' West|
|Latitude & Longitude (decimal):||33.05722,-116.79306|
|Köppen climate type:||Csa : Hot-summer Mediterranean climate|
A gemstone and mineral specimen mine developed in pegmatite which is located 7.1 km (4.4 miles) ENE of Ramona. One of the prime locations in North America for natural blue topaz. Major finds were made in 1976 and 1991. It is important to note that spessartite labeled as from the Little Three Mine is found on the adjacent Hercules pegmatite dike, a distinctly separate deposit which is also exposed on the property.
A very fine topaz-elbaite matrix specimen weighing about 150 pounds was mined in 1905 from the Little Three Mine main dike. The specimen was placed on display for many years at the San Diego Chamber of Commerce until it was moved to the newly opened Natural History Museum. During World War II, the Navy took over the museum, and the displays were crated and stored away. The specimen hasn't been seen again, and it is said to have likely been put onto a junk barge, and dumped into the ocean.
39 valid minerals. 1 (TL) - type locality of valid minerals.
This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.
Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org
|Late Cretaceous - Middle Jurassic|
66 - 174.1 Ma
|Mesozoic granitic rocks, unit 2 (Peninsular Ranges)|
Age: Mesozoic (66 - 174.1 Ma)
Stratigraphic Name: Bonsall Tonalite; Bradley Granodiorite; Cactus Quartz Monzonite; Cajalco Quartz Monzonite; Corona Hornblende Granodiorite Porphyry; Domenigoni Valley Granodiorite; Escondido Creek Leucogranodiorite; Estelle Tonalite; Fargo Canyon Diorite; Green Valley Tonalite; Home Gardens Quartz Monzonite Porphyry; Indian Mountain Leucogranodiorite; Lakeview Mountain Tonalite; Lake Wolford Leucogranodiorite; La Sierra Tonalite; Mount Hole Granodiorite; Rattlesnake Granite; Roblar Leucogranite; San Jacinto Granodiorite; Stonewall Quartz Diorite; Woodson Mountain Granodiorite
Comments: Peninsular Ranges. Primarily tonalite, granodiorite, and minor quartz monzonite and granite. Emplacement ages mostly 80 to 105 Ma in eastern part of area and 105 to 140 Ma in western part; minor Jurassic rocks in central part
Reference: Horton, J.D., C.A. San Juan, and D.B. Stoeser. The State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States. doi: 10.3133/ds1052. U.S. Geological Survey Data Series 1052.