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BLUE CAP TOURMALINE Tourmaline Queen Mine, Pala District, San Diego County, California, USA. Overall measurements are 4 ½ x by 4 ½ x 2 ¾ inches
fuckyeahcrystals: Tourmaline. Tourmaline is a piezoelectric material. Piezoelectrics generate a voltage when compressed along a perpendicular direction. Materials optimized for these properties are commonly used in sensors, scales, speakers, motors, and microscopes.