tour·ma·line 
(trmə-lĭn, -lēn′)
(trmə-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.]