Features:

1) Rocks made of calcite

2) Most limestone is grey, but all colors of limestone from white to black have

    been found

3) Scientists test natural rocks to see if they are limestones by pouring cold 

    diluted hydrochloric or sulphuric acid (10% solution or vinegar) on them

4)Gives off bubbles of carbon dioxide

5) Usage:

    a) Neutralization of acid lake waters, soil stabilization and pH control 

    b) Neutralizes sulphur dioxide gases from industrial processes such as 

        smelting metal ores and coal fired generating stations 

    d) Aggregates for concrete and road building 

    e) Artificial waterfalls and asphalt 

    f) For cosmetics and bleaching cotton

    g) Purification of dyes, oils and gasoline 

    h) Fungicides, glass, glue and gelatine 

    i) Hazardous waste disposal, PCB sludge solidification and neutralization 

    j) Ore extraction, paint and paper production 

    k) Pharmaceuticals, asprin and penicillin 

    l) Plastic, shell forming material, road beds, rubber, soap and soda pop

    m) Solid waste disposal: stabilizes sludge from sewage and desulphurizing

         plants

    n) Smelting iron ore, steel making and tanning of leather 

    o) Toothpaste, and waste water treatment, removing phosphorous and

         nitrogen, odor control, killing bacteria and aids in clarification