In cross section, all tourmalines will appear predominantly triangular in shape with some crystals showing a hexagon when three secondary prism faces are nearly as dominant as the three primary prism faces. Doubly terminated crystals are hemimorphic meaning that the two ends of the crystal are not exactly alike. The terminations on a doubly terminated crystal can have different slants to the pyramids on opposite ends. Acicular and massive forms can also be found. Cleavage is absent although there is basal parting.
Fracture is uneven to conchoidal.
Streak is white. Associated Minerals include those minerals associated with granitic pegmatites and metamorphic rocks such as micas , feldspars , quartz and even other gem minerals such as beryl , garnets , spodumene and topaz . Best Field Indicators are crystal habit, triangular cross-section, color and hardness.