The terminations can be either a simple to complex trigonal pyramid or a flat basal face. The prism faces are striated lengthwise. In cross section, all tourmalines will appear predominantly triangular in shape with some crystals showing a hexagon. Doubly terminated crystals are hemimorphic meaning that the two ends of the crystal are not exactly alike. Massive specimens can also be found.
Cleavage is absent although there is basal parting.
Fracture is uneven to conchoidal. Associated Minerals include those commonly found in volcanic rocks. Notable Occurrences is mostly limited to San Luis Potasi, Mexico. Best Field Indicators are crystal habit, triangular cross-section, locality, environment, color and hardness.