LITHIA PEGMATITE
The Pala Pegmatite of southern California is
unusual for having pockets of lithium-rich minerals. The samples shown
below are lithia pegmatites consisting of grayish-purple lepidolite
mica (KLi2Al(Al,Si)3O10(F,OH)2
- potassium lithium fluoro-hydroxy-aluminosilicate) and deep pink rubellite
tourmaline (Na(Li,Al)3Al6(BO3)3Si6O18(OH)4
- sodium lithium hydroxy-boro-aluminosilicate).
The lithia pegmatites occur as pockets within the
granitic Pala Pegmatite (Peninsula Ranges Batholith/Southern California
Batholith). The Pala Pegmatite was emplaced about 104-105 million years
ago, during the Albian Stage of the late Early Cretaceous.
Locality:
Stewart Mine, NNE of the town of Pala, northwestern San Diego County, southern
California, USA (33¼ 22Õ 52Ó North latitude, 117¼ 03Õ 49Ó West longitude)
Lithia pegmatite (3.9 cm across) with deep purplish-pink rubellite
tourmalines in a matrix of dark lavender lepidolite mica.
Lithia pegmatite (4.9 cm across) with radiating spray of dark pinkish
rubellite tourmaline in a matrix of pale lavender lepidolite mica.
Lithia pegmatite with radiating clusters of dark pinkish rubellite
tourmaline in lepidolite mica matrix. (Colorado School of Mines Geology
Museum, Golden, Colorado, USA)