Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate (CaCO3). we can reach up to 45 micron. Uses limestone: 1- Portland cement industry: about 76 % that mix with nonmetallic minerals which is chemically treated. 2- Anhydrous sod carbonates: which is important to glass industry, detergence industry, purification industry, by reaction of co2 produce from calcinations with sod chloride and ammonia. 3- Catalyst in iron kilns: that iron have silica and ammonia as impurities which removed by limestone, they found that 410 kg of limestone produce 1 ton of iron. 4- Rocky fiber: by melting limestone in kilns and pumping steam strongly, so fiber formed which use as thermal isolation. 5- Lime industry: limestone is fired to lose co2 with 44 % from its weight leaving cao, that happen at 1000 – 1100 degree, which use in glass, paper building industry. 6- Metal filler: easy to grind, low oil absorption, do not cause machine corrosion isolation of tank and roofs,, painting and ceramic industries. 7- Food industry: the pure one for birds, treatment for sugar. 8- Ornamental stone: and building. 9- paper: In alkaline papermaking, calcium carbonate is used as a paper filler and coating. Both uses require high brightness, high purity, small particle size, and lack of abrasion. 10- coating: used white pigment in paints because it is available at relatively low cost and has high brightness for TiO2 extension, high purity, low abrasivity, and resistance to weathering. 11- plastic and rubber industry: used filler in plastics due to its low cost, low abrasion, low oil absorption, low moisture, high brightness, and easy dispersion with conventional mixing equipment, In plastics they are used to improve mar and impact resistance, surface gloss, weatherability, shrin