Black Tourmaline is an excellent grounding crystal for meditation and healing.

Wear this crystal for protection against moaners, whiners, complaining neighbors or emotional vampires who burden you with their problems but do nothing to improve their situations. [Eason, 204]
In the workplace, hold Black Tourmaline for a few minutes when you need to wake up your mind or when you need full concentration. It provides an excellent shield against environmental pollutants, electromagnetic smog, and radiation associated with cell phones, computers, and other electronic equipment.