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What are the characteristics of wollastonite?
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  • 发布时间:2020-04-10 10:45
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In the field of chemistry, I believe that wollastonite is not unfamiliar, but rather familiar, so what is wollastonite? The composition of wollastonite is CA3 [si3o9]. Triclinic system belongs to single chain silicate mineral. They are usually lamellar, radial or fibrous aggregates. White with gray tinge. How much do you know about wollastonite? For your convenience, I make the following summary.
The characteristics of wollastonite are as follows:
Wollastonite belongs to a kind of chain like metasilicate, and it is also a kind of fibrous and needle like. Because of its special crystal shape
The crystalline structure of wollastonite determines its properties. Wollastonite has good insulation, high whiteness, good dielectric property, high heat resistance and weather resistance. Wollastonite is widely used in ceramics, chemical industry, metallurgy, papermaking, plastics, coatings and other fields.
The chemical formula of wollastonite is CaSiO3, [1] structural formula is CA3 [si3o9], theoretical chemical composition is Cao 48.25%, SiO2 51.75%. Pure wollastonite is rare in nature. In the process of its formation, CA is sometimes partially replaced by Fe, Mn, Ti and Sr plasmas to form isomorphic bodies, [2] mixed with a small amount of Al and a small amount of K and Na. Due to the different temperature, pressure and other conditions during the formation of wollastonite, three kinds of homomorphic polyhedron may appear:
① TC type wollastonite with triclinic chain structure is generally called low temperature triclinic wollastonite (α - CaSiO3);
② ZM type parawollastonite with monoclinic chain structure is generally called as parawollastonite (α′ - CaSiO3);
③ The PSEUDOWOLLASTONITE with triclinic ternary ring structure is generally called PSEUDOWOLLASTONITE (β - CaSiO3).
Low temperature triclinic wollastonite is widely used as industrial mineral raw material.
The low-temperature triclinic wollastonite is triclinic system, most of which are needle like, fiber like or flake like, and some of them are fan-shaped and radiation like, some of them are fine particles. The cleavage surface is pearl luster, and the cleavage is parallel and medium. The intersection angle of the cleavage surface of the two groups is 74 °. The density is 2.78-2.91 g / cm3, the hardness is 4.5-5, and the melting point is 154 ℃. The coefficient of thermal expansion is low, which is 6.5 × 10-6 mm / (mm ·℃) at 25-800 ℃; it can be converted to PSEUDOWOLLASTONITE at 1125 ℃. At this time, the coefficient of thermal expansion increases, and the color changes from white to cream, red or brown due to the release of Fe, Sr and other impurities. There are two natural types of wollastonite ore: skarn type ore and wollastonite quartz calcite type ore. The former mainly occurs in skarn deposits, with complex mineral components, often associated with quartz, calcite, diopside, garnet and other skarn minerals; the latter mainly occurs in contact metamorphic and regional metamorphic deposits, with simple mineral components, and can be divided into: wollastonite quartz, wollastonite calcite and wollastonite quartz calcite subtypes. There are usually two kinds of structural structures of wollastonite ore: dense massive ore with fine-grained granodiorite or fibrous crystallographic structure, dense massive structure, wollastonite with fine-grained, columnar or fibrous aggregate, and some very fine-grained dense ones with jade shape; coarse-grained wollastonite ore with fibrous dimensional crystallographic structure, massive, breccia like, giant porphyritic or strip structure, wollastonite with coarse-grained crystal In the shape of plate column, bundle or radial (chrysanthemum).