(n.) A mineral occurring usually in three-sided or six-sided prisms terminated by rhombohedral or scalenohedral planes. Black tourmaline (schorl) is the most common variety, but there are also other varieties, as the blue (indicolite), red (rubellite), also green, brown, and white. The red and green varieties when transparent are valued as jewels.
Webster's Revised Unabridged Dictionary
| APA | Webster's. (2011). tourmaline. Retrieved September 26, 2026, from http://smartdefine.org/tourmaline/definitions/2073579 |
| Chicago | Webster's. 2011. "tourmaline" http://smartdefine.org/tourmaline/definitions/2073579 (accessed September 26, 2026). |
| Harvard | Webster's 2011, tourmaline, Smart Define, viewed 26 September, 2026, <http://smartdefine.org/tourmaline/definitions/2073579>. |
| MLA | Webster's. "tourmaline" 28 May 2011. Web. 26 September 2026. <http://smartdefine.org/tourmaline/definitions/2073579> |