Amethyst is the purple variety of the quartz crystal. Amethyst crystal has one of the strongest powers against negative influences in your home or workplace. Amethyst is helpful to calm an overworked and over stressed mind. It is thought to dispel negativity and create a peaceful environment. As a healing stone it is said to be helpful in ridding nightmares. Just hold the Amethyst crystal on the forehead for a minute and ask it to guide you through a peaceful sleep, then place it under your pillow.