conchoidal

3

Tourmaline

  • Crystal System: Hexagonal/Trigonal
  • Hardness: 7-7.5
  • Fracture: Uneven-Conchoidal
  • Specific Gravity: 3-3.2
  • Luster: Vitreous

The name tourmaline refers to a family of cyclosilicates, that have varied composition, but the same basic crystal structure (FeWO4). There are 11 minerals in this family, including elbaite (the best and most abundant gemstone-quality tourmaline), schorl (the most common variety), and indicolite (blue tourmaline). Tourmaline is extremely common, but most of it is dark, opaque, and ugly. However, the transparent stones are highly valued. The best formed crystals are almost exclusively found in pegmatites, typically elbaite. Tourmaline is known for it’s “watermelon” gems, which are pink on the inside with green surrounding it. It also is the state gem of Maine, due to the high quality gems produced by the Mica Mines. So sorry about the long hiatus, but I recently went to the Smithsonian and they had so many cool rocks, so I’m back! Please, please ask me things!!!