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 (33º 22’ 52” North latitude, 117º 03’ 49” 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)