[Chemical composition] The composition is more complex than other hornblende minerals, and there are many similar types of similar species. A wide variety of isomorphic substitutions appear in the A, X, and Y cations. The composition of the common hornblende can also be seen as a series of tremolite -raiseite series, that is, part of Si is replaced by Al, and corresponding part of Mg is replaced by Al and Fe 3+ , and Na+ is added. In ordinary hornblende, Al exists in two ways, and sometimes the content of K can exceed Na. In addition, it usually contains 0.1% to 1.25% of TiO 2 . [Crystal structure] monoclinic system; [Form] It is often a columnar crystal (Fig. G-36). The cross section is a pseudo hexagon. The double crystal is {100} in contact with the twin crystal. It is often a fine columnar, fibrous aggregate. Figure G-36 ordinary amphibole crystal Oblique column: m{110}, r{011}, i{031}; parallel double-sided: b{010}, c{001}, e{101} [Physical properties] dark green to black green; streaks are colorless or white; glass luster. The cleavage {110} is complete, and the two sets of cleavage angles are 124° or 56°; sometimes the {100} cracking is caused by the influence of the polycrystalline twin crystal. Hardness 5 to 6. The relative density is 3.1 to 3.3. [genesis and occurrence] is closely related to magmatism and is the main constituent mineral of various medium and acidic intrusive rocks. A common hornblende variant rich in Fe 2 O 3 and TiO 2 found in basic spouted rock is called basaltic hornblende. Ordinary hornblende sometimes forms an illusion by pyroxene, which is called a fake amphibole. Among the products of regional metamorphism, it is the main component of amphibolite , hornblende schist, and hornblende gneiss . [identification characteristics] color, columnar crystal form, two sets of complete columnar cleavage. The difference from ordinary pyroxene is that the angle of hornblende cleavage is 124° or 56°, and the section is diamond or nearly diamond. [Main use] See the Asbestos family asbestos . Tungsten Powder,Plasma Spray Powder,Pure Tungsten Powder,Tungsten Metal Powder Luoyang Golden Egret Geotools Co., Ltd , https://www.xtchvof.com
a 0 = 0.979 nm, b 0 = 1.790 nm, c 0 = 0.528 nm; β = 105 ° 31 '; Z = 2. The crystal structure characteristics are summarized in the hornblende family.
Ordinary hornblende (Hornblende)
Ca 2 Na(Mg,Fe) 4 (Al,Fe 3+ )[(Si,Al) 4 O 11 ] 2 (OH) 2