polychrome tourmaline

The name tourmaline derives from the Sinhalese word “turamali”. It was generally used to identify colored stones that came from Sri Lanka. The tourmaline group recognizes numerous mineralogical species within it. The reason is given by the fact that unlike most others, the chemical composition of the varieties that are part of it is particularly complex and changeable from one another. This in fact depends on the intricate and unlimited isomorphic substitutions. Tourmaline is a typical mineral of pegmatitic rocks, it can also be found in metamorphic rocks, and in sedimentary rocks as a detrital mineral; it crystallizes in the trigonal system, its crystalline habit is prismatic, pseudo-hexagonal with two flattened pyramids at the ends.