Elbaite, Dravite, Schorl
Light To Strong Pink, Orangy Red, Red, Purplish Red, Purple, Inky Blue, Blue, Bluish Violet, Violet, Greenish Blue, Light To Dark Green-Blue To Yellowish Green, Dark Green, Yellow, Orange, Brown, Dark Brown, Black, Rarely Colorless
Achroite, Bi-Color Or Parti-Colored, Chrome Tourmaline, Dravite, Elbaite, Fluor-Buergerite, Indicolite, Liddicoatite, Povondtaite, ParaBa Tourmaline, Rubellite, Schorl, Uvite, Verdelite, Watermelon
appearance, refractive index and high birefringence; then optic figure, pleochroism and specific gravity
Crystal habit is prismatic and may be 3, 6 or 9-sided; often a triangular prism with convex faces, and often long and heavily striated parallel to the c axis. Pyramidal terminations are common. Misnomers: Brazilian sapphire-blue tourmaline; Brazilian emerald, Ceylonese peridot-green tourmaline. Achroite: colorlessBi-color or parti-colored: tourmaline with two colors and multiple colors. Chrome tourmaline: fine intense green usually colored by chrome or vanadium. Dravite: yellow or brown tourmaline. Elbaite: a sodium lithium aluminum tourmaline species. Fluor-buergerite: bronzish-brown to dark-brown to almost black with bronze schiller. Indicolite or indigolite: violetish blue to greenish blue. Liddicoatite: a calcium lithium tourmaline species. Povondtaite: dark brown, brownish black to black with resinous luster. Paraba tourmaline: a neon blue to green colored cuprian Elbaite tourmaline originally found in the Brazilian State of Paraiba. Rubellite: deep pink to red stones. Schorl: black, brownish black or blueish black stones. Uvite: a calcium magnesium aluminum tourmaline species. Verdelite: dark green,yellowish green, brownish green to blueish green. Watermelon: pink center with green edges. Birefringence is typically around 0.020 but dark material can be up to 0.040 October birthstone. Pyroelectric: development of opposite charges at the ends of a tourmaline crystal due to change in temperature. Piezoelectric: development of opposite charges at the ends of a tourmaline crystal when placed under stress.