Explanation
silicate mineral with ring structure. According to different cations, there are clravite, black tourmaline, elbaite and other minerals. Trilateral system, space group CSV-R3m. Cylindrical or acicular crystal, often with longitudinal lines on the cylindrical surface, and the cross section of crystal is arc triangle. tourmaline rich in magnesium is brown or yellow, tourmaline containing iron is black, and tourmaline containing lithium, manganese and cesium is light green. Often, different colored rings appear on the cross-section, or different color bands appear at the upper and lower ends of the column. glass lustre. Morse hardness 7, staggered fracture, density 3.03-3.25g/cm ^ 3. It mainly occurs in granitic pegmatite, gas generated high-temperature hydrothermal veins and greisen, and coexists with beryl and columbite-tantalite. It also occurs in metamorphic rock and coexists with biotite and garnet. Transparent and bright color can be used as gems. crystal with obvious piezoelectricity and pyroelectric properties and good pyroelectric properties can be used in the radio industry. It can release far infrared ray and produce negative ions, and can be used to prepare environmental materials.
Classification
Natural materials and products -> Mineral materials