April 2025 – Tourmaline

Our mineral of the month for April is tourmaline. Tourmaline is a mineral with a very complex chemical composition and variability. This means that it can have many different colours. The physical phenomenon of pyroelectricity was first discovered in tourmaline crystals. When a tourmaline crystal is heated, its two ends become oppositely charged and can attract light objects such as leaves or ash.

Chemical formula: (Ca,K,Na,▢)(Al,Fe,Li,Mg,Mn)₃(Al,Cr,Fe,V)₆(BO₃)₃(Si,Al,B)₆O₁₈(OH,F)₄

Locality: Minas Gerais, Brazil

Size: 8 x 5 x 4 cm

Weight: 236 g