Tourmaline is a group of complex silicate minerals that can occur in almost all colours of the rainbow. It is known for its pyroelectric properties (attracts ash when rubbed).
Significant deposits are found in Brazil and Africa. Tourmaline is considered one of the strongest protective stones. The colourful varieties, such as watermelon tourmaline, harmonise heart and mind, while dravite (brown) has a particularly grounding effect.
