(1) chemical composition: C. It often contains chromium, manganese, titanium, magnesium, aluminum, calcium, silicon, nitrogen, boron, etc.
(2) Color: light yellow, light yellow brown, light yellow green and brown are common, and colorless (light yellow white, white and excellent white) occupies a certain amount, while rose red, pink, light blue, green, black and brown are very rare.
(3) Transparency: colorless and light-colored diamonds are transparent, and the transparency of colorless white diamonds and excellent white diamonds is above 95%, while the transparency of dark diamonds and ground glass etching is translucent, and the increase of inclusions in diamonds will also affect the transparency.
(4) Hardness: Mohs hardness 10, new Mohs hardness 15, microhardness 10000kg/mm2, microhardness is 1000 times higher than that of the corresponding time and 150 times higher than that of corundum. The hardness of diamond is directional. The hardness of octahedral crystal face is greater than that of rhombohedral crystal face, and the hardness of rhombohedral crystal face is greater than that of hexahedral crystal face.
(5) Density: The density of a diamond is closely related to the inclusions in the diamond crystal. The density of colorless transparent pure diamond is 3.52g/cm3, and it is 3.44~3.53g/cm3 with inclusion.
(6) Polarization: Most diamonds show inhomogeneity under polarized light. Diamonds belong to equiaxed minerals and should be homogeneous in theory. However, diamond is formed in the geological body with changing pressure, and the internal structure of diamond crystal is partially dislocated due to stress, thus showing uneven inhomogeneity, which is manifested as first-class gray with inconsistent extinction and extremely low interference color, and a few uniaxial crystal interference images can be measured.
(7) refractive index (n): 2.4493 (λ 436 μ m), 2.4354(λ486μm), 2.4237(λ546μm), 2.4 176(λ589μm), 2.4103 (λ 655).
(8) Reflectivity (r): 5.308% in oil and 65,438+07.29% in air.
(9) Hydrophilic and hydrophobic: Diamond is an oleophilic and hydrophobic mineral, and a halo can be seen on the crystal surface after rubbing with oil. Droplets of oil will spread immediately on the crystal surface, but drops of water will not. Therefore, diamond can be separated by oil separation in mineral processing.
(10) electromagnetism: diamond is a non-magnetic heavy mineral (p & gt2.9), so electromagnetic separation (medium magnetism and weak magnetism) cannot be used for mineral processing.
(1 1) conductivity: most diamonds are dielectric, with a resistivity of 5×104Ω. cm, and type I and type II (IIA) diamonds are insulators, with a specific resistance >:1016Ω. Cm, I-type (H b) diamond is a P-type semiconductor, and its resistivity is10 ~103 Ω.cm. When the temperature rises to 600℃ or falls to-150℃, the resistance increases.
(12) Stiffness and strength: Diamond has a great elastic modulus, which is the highest abrasive material in nature, with an elastic modulus as high as 90000 kg/mm ... with a small friction coefficient and extremely high wear resistance. Therefore, in diamond dressing, ball mills and cone mills are used to separate diamonds. However, diamonds are extremely fragile and cannot withstand the impact of positive external forces.
(13) melting point: the melting point of diamond reaches 4000℃, and the combustion temperature in air is 850~ 1000℃. When it burns in pure oxygen at 720~800℃, the diamond emits a light blue flame and is converted into carbon dioxide.
(14) luminescence: diamonds produce sky blue and light green fluorescence under X-rays, light yellow and sky blue fluorescence under long-wave and short-wave ultraviolet rays, but a considerable part of them do not emit light. Some will emit light blue phosphorescence under sunlight. Under cathode ray, it shows blue and green fluorescence.
(15) luster: It belongs to the standard diamond luster, and the grease luster or luster may be weakened due to melting and ground glass etching.
(16) dispersion: diamond dispersion is 0.044. Under the irradiation of natural light, a certain incident angle produces a decomposed spectral color on the diamond surface, commonly known as fire color (the strength of diamond fire color is also related to body color, clarity, facet angle, etc.).
(17) thermal conductivity: diamond has good thermal conductivity, with the thermal conductivity as high as 669.89~2009.66W/(m? Type Ⅱ (Ⅱ A) diamond has excellent thermal conductivity, which is 2.5 times that of copper at liquid nitrogen temperature and 5 times that of copper at room temperature.
(18) thermal expansion: the thermal expansion coefficient is small.
(19) Cleavage: |11| Medium, |1/kloc-0 | Incomplete.
(20) Fracture: See shell shape.
(2 1) chemical stability: very stable in chemical properties, insoluble in acid and alkali, soluble in molten sodium nitrate, potassium nitrate and sodium carbonate.