Talcum, Talc, French Chalk are all Magnesuim Silicate. Chalk is a type of limestone, a form of calcium carbonate. Blackboard chalk, confusingly, tends to be made from calcium sulfate. David. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech_ptg.org/attachments/20090109/bdd98731/attachment.html>
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