Black Amethyst is Amethyst that is heavily included with Hematite that it appears black with tints of violet.
All types of Amethyst are good psychic protection stones, but in addition the black stones have a good grounding vibration. The crystal properties of Black Amethyst also makes them excellent healing stones, that help rejuvenate your entire system. This is a helpful stone for healers to use on days when you have perhaps done to much and need to pick up and replenish your energy. Photo is a sample.