[meteorite-list] another cleaning irons question

[Michael Murray]

I have a couple small suspect irons that I would like to be able to  
finally get to see but they both have a rind of stone-like material  
completely encasing them.  Probably calcium.  I know there are several  
household products that are supposed to remove calcium but will they  
ruin my little iron?  Who can recommend a trustworthy product to use  
for getting the stone-like material off without it ruining what is  
underneath?

Mike in CO