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This list is for people who like Tourmaline.
Scientific Data
Physical properties: Hardness of 7 to 7.5, brittle, conchoidal fracture, no cleavage, specific gravity a little over 3, transparent to translucent, colorless streak, vitreous to resinous luster. Occasionally pleochroic or chatoyant. Strongly piezoelectric and pyroelectric. Insoluble in acids.
Tourmaline Group Members
Buergerite Na Fe3+3Al6(BO3)3Si6O18(O)3(OH)
Dark brown to black crystals, in divergent sprays, to 4 cm long. Uncommon, from Mexquitic, San Luis Potosi, Mexico, where it occurs in hydrothermally altered tuffs in clay seams in rhyolite. Panczner (1987) in Minerals of Mexico states: "This is the type location for this mineral, but the exact location is unknown. The man who discovered and mined all the buergerite that reached the mineral world has died and told no one the exact location." This appears to be the only locality for buergerite.
Chromdravite NaMg3[Cr,Fe3+]6(BO3)3Si6O18(OH)4
Very rare, found as dark green crystals and grains to perhaps a few mm, in micaceous metasomatic clay-carbonate rocks at the Velikaya Guba uranium occurrence, Zaonezhskii Peninsula, Onezhkii basin, central Karelia, Russia.
Dravite NaMg3Al6(BO3)3Si6O18(OH)4
Crystals are stubby to long prismatic, often striated vertically. Colors include brown, black, greenish-black, dark red, and pale bluish-green to emerald green. Found in many places, includint many in the US, and Austria, Kazakhstan, Kenya, and Brazil, but the best and most famous crystals are probably those from Yinnietharra, Western Australia, where sharp complete doubly-terminated brown crystals to the size of a softball (surprisingly nonhemimorphic!) have been found. Not hard to obtain.
Elbaite Na(Li1.5Al1.5)Al6(BO3)3Si6O18(OH)4
This is the most famous tourmaline group member, occurring in many colors, including red, green, blue, yellow, and rarely colorless. Crystals are short to long prismatic, vertically striated, occasionally acicular or other habits. Elbaite most often occurs in granite pegmatites, and is found in fine crystals at numerous localities all over the world. Famous localities include the Himalaya Mine in California; Mount Mica in Maine; Elba Island in Italy; and many mines in Brazil. Crystals to 1.6 meters long have been found. Click here to see a couple of nice elbaites from CA and Brazil.
Feruvite CaFe2+3[Al5Mg](BO3)3Si6O18(OH)4
Rare, dark brown-black grains to 2 millimeters, usually zoned with feruvite, dravite, and schorl intergrowths. First found on Cuvier Island, New Zealand; also known from Red Cross Lake, Manitoba; and the Sullivan deposit, British Columbia. Formed by hydrothermal replacement of silicates in a pegmatitic rock.
Foitite [Fe2+2(Al,Fe3+)]Al6(BO3)3Si6O18(OH)4
Dark indigo to black, typical prismatic striated crystals with triangular cross-section, found in crystals to a few cm in California's White Queen Mine. Known from a few other localities in Montana, Italy, Czech Republic, and Australia.
Liddicoatite Ca(Li2Al)Al6(BO3)3Si6O18(OH)4
Found in stout crystals, up to 25x10 centimeters, striated along their lengths. Astonishing and complex multi-colored color-zoning, in triangular patterns, is exposed when crystals are cut perpendicular to their elongation. The best are found in pegmatites in various parts of Madagascar, also some from the Czech Republic, Russia, and Brazil. The polished slabs are beautiful but very expensive.
Magnesiofoitite [Mg2+2(Al3+)]Al6(BO3)3Si6O18(OH)4
New and rare, found as very small acicular greyish crystals on matrix, from the Kyonasawa area, Mitomi-Mura, Yamanashi-Ken, Honshu, Japan.
Olenite NaAl3Al6(BO3)3Si6O18(O)3(OH)
Rare, vitreous pale pink. Found in granitic pegmatites as zones in elbaite crystals to a few cm, from the Decembrist pegmatite field, Olenek River Basin, Russia; and Elba Italy. Also from Maine, California, and North Carolina.
Povondraite NaFe3+3Fe3+6(BO3)3Si6O18(O)3(OH)
Very rare, black crystals to 3 mm, in clusters to 1 cm. Found in fractures and lining cavities in schist metamorphosed from sedimentary rocks, at Cristalmuya gorge, 200 m downhill from the San Francisco Mine, 50 km from Villa Tunari, Alto Chapare Province, Cochabamba Dept., Bolivia.
Rossmanite (LiAl2)Al6(BO3)3Si6O18(OH)4
New and rare, pale pink prismatic striated crystals 5 mm thick x 25 mm long, associated with elbaite in lepidolite, from the Rozna pegmatite, Hradisko Quarry, near Rozna, western Moravia, Czech Republic
Schorl NaFe2+3Al6(BO3)3Si6O18(OH)4
Usually black, rarely dark brown, blue, green.. Superb lustrous sharp crystals, from granite pegmatites, quartz veins, greisens, schists, gneisses, and phyllites. Localities for fine xls are numerous, including California, Maine, Brazil, Pakistan and Afghanistan, and others. Crystals to 1.5 meters have been found.
Uvite CaMg3[Al5Mg](BO3)3Si6O18(OH)4
Crystals are often equant, as well short to long prismatic. Colors include black, red, green and brown. Lustrous sharp equant black crystals found at several localities in New York State, as well as Burma, Sri Lanka, Kenya, and many other places. Finest specimens are bright red or green crystals on quartz or magnesite crystals from Brumhado, Brazil