[too
r-muh-lin, -leen] 
| any of a group of silicate minerals of complex composition, containing boron, aluminum, etc., usually black but having various colored, transparent varieties used as gems. |
[toor-muh-lin-ik] , adjective | tour·ma·line (tŏŏr'mə-lĭn, -lēn') n. A complex crystalline silicate containing aluminum, boron, and other elements, used in electronic instrumentation and, especially in its green, clear, and blue varieties, as a gemstone. [French, from Sinhalese toramalli, carnelian.] |
tourmaline (t r'mə-lĭn, -lēn') Pronunciation Key
Any of several minerals having the general chemical formula (Na,Ca)(Mg,Fe,Al,Li)3Al6(BO3)3Si6O18(OH)4. Tourmaline occurs in many different translucent colors, usually in crystals shaped like 3-, 6-, or 9-sided prisms. It occurs in igneous and metamorphic rocks, especially in pegmatites. |