Tourmaline Group (Schorl and Elbaite) - Schorl: NaFe²⁺₃Al₆(BO₃)₃Si₆O₁₈(OH)₄ Elbaite: Na(Al_1.5Li_1.5)Al₆(BO₃)₃Si₆O₁₈(OH)₄

Habit: Black, brownish black or bluish black (schorl); green, blue, red, orange, yellow or colorless (elbaite); zoning common, parallel to trigonal outline (both). Crystals prismatic to acicular, with prominent trigonal prism and pyramid, commonly hemimorphic; also radial, fibrous or massive. Vitreous to resinous luster; transparent to translucent to nearly opaque. White streak.

Environment: Both types found in granites and granite pegmatites, high-temperature hydrothermal veins and some metamorphic rocks; also as detrital sediments.

Etymology: Schorl comes from the Old German Schürl, which perhaps means "impurities." Elbaite is named from its occurrence on the island of Elba, Italy.

The tourmaline group includes many minerals of different chemistries and therefore different colors. The black version, schorl, is the most common, accounting for more than 95 percent. The remaining 5 percent represents the more attractive, gem-quality stones