... visibility Good qualified rate Timely delivery Dust free Not discolor,peel,char,crack IntroductionDescription:Soapstone chalk Item No.: SP1011 Size: 100 ... Moh'sSilica:60% ± 1Magnesium oxide:≥ 30%Finish:Not polishingCertification:ISO9001Characteristics:Dust free, high visibility. Not run, char, discolor, peel or ... manufacturing, Vehicles manufacturing, ship manufacturing, steel factory, etc Talcum chalk