The sillite stone is also called sillimanite or sillimanite, which is a brown, light green, light blue or white glassy silicate mineral. The crystals of the sillimanite are columnar or needle-like, and these crystals are often polymerized together in a fibrous or radial form, and have a silk luster or a glass luster. After the stone is heated, it can be turned into mullite and used as a high-grade refractory. Named after the American chemist Benjamin Silliman. The sillimanite is a typical high-temperature metamorphic mineral, which is formed by the metamorphism of high-altitude argillaceous rocks and is produced in crystalline schist and gneiss; it is also found in the contact zone between the aluminum-rich rock and the igneous rock. When the stone is heated to 1300 ° C, it becomes mullite and can be used as a high-grade refractory material. In the crystal structure, two kinds of tetrahedrons [SiO4] and [AlO4] are alternately arranged along the Z axis to form an aluminosilicate [AlSiO5] double chain. The crystal is columnar and needle-shaped, and the aggregate is fibrous. White, grayish white, can also be light brown, light green, light blue, glass luster or silky luster, the board surface is completely cleavable. The Moss hardness is 6.7 to 7.5, and the specific gravity is 3.23 to 3.27. Molecular formula Al2[SIO4]O, theoretical composition (wB%): SiO237.1, Al2O362.90. Al in andalusite can be replaced by Fe (≤9.6%) and Mn (≤7.7%). Kyanite may contain Cr (≤12.8%), and also often contains Fe (1~2%) and a small amount of Ca, Mg, Fe, Ti and the like. The sillimanite composition is relatively stable, and a small amount of Fe replaces Al, and may contain trace amounts of Ti, Ca, Fe, Mg, and the like. Orthorhombic system, 0=0.744, b0=0.760, c0=0.575. The crystal is long column or needle. There are stripes on the cylinder of the crystal strip. The aggregate is radial or fibrous. Sometimes it is hairy and exists as an inclusion in quartz and feldspar crystals. The hairy ceremonial stone is called a thin stone. This needle-like crystal form of sillimanite is related to the presence of [SiO4] and [AlO4] double chains and [AlO6] octahedral chains in its structure. The basic structure is composed of [SiO4] and [AlO4] tetrahedrons alternately arranged along the c-axis to form [AlSiO5] double-strand; the double-chain is connected by [AlO6] octahedron, and the [AlO6] octahedron is co-edge-joined into chains. The four corners and the center of the unit cell (001) projection surface, 1/2 of Al is a quadruple coordination. The structural characteristics determine that the sillimanite has acicular c-axis extended acicular, fibrous crystal morphology and enthalpy cleavage. Weihai Jocund Home Textile Co., Ltd , https://www.jocundhome.com