tourmaline
/ˈtʊəməlɪn
/ /ˈtʊəməliːn/noun [mass noun]
A typically black or blackish mineral that occurs as prismatic crystals in granitic and other rocks. It consists of a boron aluminosilicate and has pyroelectric and piezoelectric properties.In the line rock, this black tourmaline occurs as tiny prismatic crystals....
- The mineral assemblage comprises quartz, K-feldspar, albitic plagioclase, white mica, apatite, tourmaline and garnet.
- It consists of clasts of angular to rounded quartz, plagioclase, tourmaline and rock fragments, up to 3 mm in diameter.
Origin
Mid 18th century: from French, based on Sinhalese tōramalli 'carnelian'.