Pack Rat Mine, Tule Mountain (Mount Tule; Tulley Mountain), Jacumba, Jacumba District, San Diego Co., California, USA

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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.

Summary:

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.

Sample Data:

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.

References

Todd, V. R. et al. (1987). Mineral Resources of the Sawtooth Mountains and Carrizo Gorge/ Eastern McCain Valley Wilderness Study Areas, San Diego County, California. U.S. Geological Survey Bulletin 1711-B, 26 p., maps.

Mineral List

Albite 'Apatite' Beryl var: Aquamarine var: Goshenite Cassiterite Columbite Danburite

Eosphorite Frondelite 'Garnet' Helvite Herderite Hureaulite Hydroxylherderite Lithiophilite

Microcline Mitridatite Montmorillonite Muscovite Phosphosiderite Purpurite Quartz Robertsite

Schorl Spessartine Spodumene var: Kunzite Strengite Tantalite

29 entries listed. 21 valid minerals. 1 erroneous literature entry.