Pack Rat Mine, Tule Mountain (Mount Tule; Tulley Mountain), Jacumba, Jacumba District, San Diego Co., California, USA
|Latitude & Longitude (WGS84):||32° 43' 2'' North , 116° 13' 50'' West|
|Latitude & Longitude (decimal):||32.71722,-116.23056|
|Köppen climate type:||Csa : Hot-summer Mediterranean climate|
Granite pegmatite located 7.2 km (4.5 miles) NE of Boulevard; 9.1 km (5.6 miles) WSW of Dos Cabezas; and, 11.7 km (7.3 miles) NNW of Jacumba.
Several 10- to 20-foot-thick granite pegmatite dikes trend north 6 degrees west, dip 65 degrees west, and extend as far as one-half mile in schist and quartzite. Pegmatite pockets contain microcline, green muscovite, black tourmaline (schorl), columbite/tantalite, gem-grade beryl (goshenite and aquamarine), fluorapatite, spessartite, and quartz. Most pockets are filled with montmorillonite clay and range in size from a few inches to several feet.
Workings & Production:
Eight open cuts. According to the claimant in 1986, several specimens of aquamarine and garnet have been sold.
One random chip sample of green mica contained 6.1 percent potassium, 0.15 percent fluorine, 0.00069 percent beryllium, 0.028 percent lithium, 0.016 percent magnesium, and 0.055 percent manganese. Pockets within the pegmatite were observed to contain several indicator minerals of gem-bearing zones.
22 valid minerals. 1 erroneous literature entry.
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 - Paleoproterozoic|
66 - 2500 Ma
|pre-Cenozoic granitic and metamorphic rocks undivided|
Age: to Cretaceous (66 - 2500 Ma)
Stratigraphic Name: Ash Mountain Complex; Placerita Formation; Sur Series
Comments: Southern California, Mojave Desert, Sierra Nevada, central California Coast Ranges
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.