Labradorite

Labradorite is one of the group of the Felspars (q.v.), and a very important rock-forming mineral. Thus, it is a principal ingredient in many diorites, basalts, gabbros, and andesites. It is met with also in certain volcanic tuffs (Etna). As a rule it is colourless or gray, and seldom transparent. Here and there it occurs in large masses associated with schistose rocks, as on the coast of Labrador. This massive kind (Labrador stone) often shows a beautiful play of rich colours, takes a fine polish, and is cut into snuff-boxes.