Black Crystalline Tourmaline - 10 Pieces of Mineral
Black Crystalline Tourmaline, 10 Pieces
by American Scientific
A crystalline boron silicate mineral that has been compounded with other elements like aluminium, iron, and magnesium to name a few, Tourmaline is a semi-precious stone. When cut and polished, the gemstone occurs in a wide variety of colors like blue, red, green, pink, and yellow, though black and bluish-black are predominant.
Tourmaline, regardless of its color, is typically found in granite or metamorphic rocks like schist or marble. Many of the different colors of Tourmaline have magnetic susceptibilities, in particular the black and yellow due to their high concentrations of iron and manganese. Others are pyroelectric, meaning that as they are heated or cooled, they are capable of generating a temporary voltage. Unlike thermoelectricity, pyroelectricity sees the entire object generating a voltage.