Granite, the main mineral composition of pyroxene, plagioclase, a small amount of olivine, biotite and trace magnetite, black color, structural precision, after hundreds of millions of years of aging, uniform texture, good stability, strength, hardness High, can maintain high precision under heavy load. Applicable to industrial production and laboratory measurement work. Natural granite materials by mechanical processing, hand-refined from. Black luster, the structure of fine texture uniformity, good stability. Strength, high hardness. And has: no rusty acid and alkali, no magnetization, the same type, good wear resistance and so on. Can be stable at heavy load and general temperature. Granite slabs are precision benchmarking tools made of natural stone materials, and are ideal for instrumentation, precision tools, and mechanical parts. Especially for high-precision measurement, due to its unique characteristics, leaving the cast iron plate dwarfs. Granite is drawn from the underground high-quality rock layer, after hundreds of millions of years of natural aging, the shape is extremely stable, do not worry about the temperature difference due to conventional deformation. Strict physical tests and selection of granite material, crystal fine, hard texture, compressive strength of 2290-3750 kg / square centimeter, the hardness of Mohs hardness of 6-7. Very resistant to wear, acid, alkali, high corrosion resistance, never rust. As a result of granite non-metallic materials, no magnetic reaction, no plastic deformation. Its hardness is 2-3 times higher than cast iron (equivalent to HRC> 51), so the accuracy of good retention. In the use of rock tools even by heavy objects bump, up to a few pieces of ballast it, and not like a metal tool, due to deformation and damage accuracy. It is superior to high-quality cast iron and steel production of precision measurement of reference parts, you can get high and stable accuracy.