Tourmaline
Image: Robert M. Lavinsky (CC BY-SA 3.0)
Mineral NameTourmaline
Chemical FormulaNa(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)4
Mohs Hardness7
Crystal Systemtrigonal
Lustervitreous
Streak Colorwhite
Cleavageindistinct
Fractureconchoidal to uneven
Specific Gravity3.06
Colorspink, red, bluish-green
Transparencytranslucent to transparent
Type LocalityTourmaline Queen Mine, Pala District, San Diego County, California, USA
Mineral GroupSilicates
Usesjewelry, collector
Associated Mineralsquartz, albite, lepidolite
Rarityrare
Description
A large, prismatic, color-zoned tourmaline crystal, displaying a vibrant deep pink to red body transitioning to a bluish-green cap, with characteristic vertical striations.
Geological Context
Tourmaline, particularly gem-quality Elbaite, forms in granitic pegmatites, which are coarse-grained igneous rocks crystallizing from volatile-rich residual magma.
