achroite

Achroite is a colorless variety of tourmaline, a borosilicate mineral known for its complex and variable composition. Tourmaline itself comes in various colors, including black (schorl), brown (dravite), pink (rubellite), green (Brazilian emerald), and colorless. Achroite is specifically the colorless gem cut from this mineral. Tourmaline is found in pegmatites and metamorphosed limestones and is resistant to weathering, often accumulating in sedimentary deposits. Beyond its use as a gemstone, tourmaline has piezoelectric properties, allowing it to generate electric charge under mechanical stress, making it useful in pressure-measuring devices.12