Sugilite, also known as Luvulite is a recent discovery in the gem world.  It is a deep opaque purple or pink stone.
It's found in Japan, Canada, and Europe.  In 1979, a large deposit was found in South Africa.  It is typically cut into cabochons and polished.  Bright purple ones are the most valued. 

Folklore and uses:

It is said to strengthen the heart and aid healing.  It protects against negative energies and helps you stay balanced.  It can help clear the mind and prepare for the awakening of consciousness.  It helps us overcome limiting beliefs.  It's purple color would naturally benefit the head centers and the organs in the head.  I would suspect that wearing one while you sleep would help induce prophetic dreams, or at least lucid dreams.  There isn't any ancient folklore since it's so recently discovered.