Black Tourmaline is the most powerful stone for protection against negativity, particularly from people, e.g. envy. It is also a strong grounding stone.
"If you are in a time of deep personal transformation in your life, you may be wildly attracted to the beautiful, intense red and black swirls. This Tourmaline is a great talisman for transitional periods where you need to release and remove obstacles which are holding you back: divorce, leaving an abusive relationship or toxic environment, and of course letting go of our own toxic patterns, behaviours and attachments." Loa Light
It is excellent for 'female' issues around menstruation, menopause and transitioning through the stages of cycles and also motherhood. It is excellent for working in the root chakra and the sacral chakra. It is grounding and and good for protection (as we know Tourmaline to be) but particularly in the realms of issues that we encounter as women.