hi avisinai!
i don't know if this will help,  but have you heard of the vinegar test?
if you drip vinegar onto the stones which you want to put in your tank and the
vinegar has no reaction then you can use them... if it starts to react ie
bubble do NOT use them. 
i hope that this might help you even though it only answers half of your
question!!
love clairebear.
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 * RgateImp.MoonDog.BBS at 4/18/03 3:24:09 PM