Looking to buy Chalk Powder:
Specification:
Physical State                                           : Powder.
Calcium carbonate content (CaCO3)        : 94% (Min)
Acid insoluble materials                            : 6% (Max)
Organic Acid Content                                : 0.35% -0.5% 
Ignition loss                                               : 41.4 - 44%
Moisture content                                       : 0.25% (Max)
Sieve Residue:
a) 200 micron Mesh                             : Nil
b) 125 micron Mesh                             : 0.01%(Max)
Conductivity of water extract                     : 200  ms/cm (Max)