Identification characteristics of brucite

The identification features are its morphology, low hardness, and (0001) extremely complete cleavage. Tripartite crystal system, a0=0.313nm, c0=0.474nm; Z=1. The brucite type structure is one of the important layered structures. In the structure, (OH) - is approximately hexagonal tightly packed, with Mg2 filled in octahedral voids separated by a layer of stacking. Each Mg is surrounded by 6 OH, with 3 Mg on one side of each OH. The [Mg (OH) 6] octahedron {0001} is connected into layers in a co rhombic manner, with weak hydrogen oxygen bonding between the layers, forming a layered structure. Mg-OH is not a regular octahedral sheet, with significant flattening along the c-axis direction, and the sheet thickness has increased from a normal 0.247nm to 0.211nm. The structural characteristics of brucite give it a plate-like crystal shape, low hardness, and extremely complete cleavage of {0001}.


Complex trigonometric crystal class, D3d-3m (L33L33PC). The crystals are in the form of plates or leaves. Common simplex: parallel double-sided c {0001}, hexagonal column m {1120}, rhombic r {1011}, q {0113} or {2021}. Crystals are usually in the form of plate-like, fine-scale, rounded, and irregular granular aggregates; Sometimes parallel fibrous aggregates appear, called fibrous magnesite. There is structural distortion inside the fibrous brucite. White, grayish white, appearing green, yellow, or brownish red when Fe and Mn are mixed in; Fresh surface and fracture glass luster, cleavage surface pearl luster, fibrous magnesia with silk luster; Transparent. The cleavage {0001} is extremely complete. Hardness 2.5. Fine pieces have flexibility and flexibility. Relative density 2.3~2.6. It has thermoelectric properties. The whiteness of blocky brucite can reach 95%.


Under polarizer: Abnormal interference color of red brown replaces normal primary yellow or orange. Ductility can be positive or negative under the influence of stress. Uniaxial crystal (), but can exhibit biaxial crystal, 2V ? 25 ?. The refractive index Ne=1.5705~1.5861, and No=1.5612~1.570. After heating, the difference between Ne and No. decreases.


Mechanical properties: The tensile strength of fibrous brucite is 902MPa, which is a medium strength fiber material. The elastic modulus is 13800MPa, with a certain degree of brittleness. The Vickers hardness ranges from 50.4 to 260.5 and exhibits significant anisotropy. Easy to grind into fine-grained powder. Theoretical relative density 2.39.


Electromagnetic performance: The mass resistivity of fibrous magnesia is 8.82 × 106 Ω x g/cm2, the volume resistivity is 5.9 × 106 Ω x cm, the surface resistivity is 3.6~4.5 × 106 Ω, and the resistivity is anisotropic; The resistivity increases during heating. The dielectric constant is 4.7~5.4 (1MHz); Under low frequency (50Hz) and intermediate frequency conditions, the dielectric constant increases and exhibits obvious directionality; The tangent value of the dielectric loss angle is 0.105. Heating increases the dielectric constant and dielectric loss tangent by 54% and 2.7 times, respectively. The specific magnetization coefficient of fibrous magnesia is 9.815~15.779 × 10-6cm3/g, belonging to a non-magnetic mineral; Heating increases the specific magnetization coefficient, but at 300 ℃, 500 ℃, and 600 ℃