The riches of Madagascar in crystals are amazing and these are Mystic Merlinite pillows or Gabbro large tumbles. You can read more about healing properties of shape. This stone is geologically called gabbro.
Use it as a stone that will assist in aligning the chakras. And then it helps helps you to enter altered states of consciousness. It is considered magical in other words use it to link to and work with the elementals of the planet and other realms.
Also note that this size of mystic merlinite pillows will suit hemp necklaces.