Black Tourmaline can be used for protection and to repel negativity.  It protects us from being victimized by the negativity of others.  It also deflects energy.  It can increase your energy level by preventing it from being drained by others.  Black Tourmaline can be used to break spells.  Used with Mica, it returns the spell to its place of origin. 

It also helps to ground us, especially grounding between the root chakra and the center of the Earth.  The more grounded we are, the more protection we have. 

These stones also contain Brown Tourmaline which is used to clear the aura and align the energy body.