| | |   Optical polishing powder. Cerium oxide in the form of a very fine powder is used as a polishing compound for optical glass.  Supposed it works better than aluminum oxide or other abrasives in certain situations.  It's very cheap: A few dollars a pound, which tells you something about how rare the "rare" earths actually are, which is not very.
 Source: eBay seller fellows
 Contributor: Theodore Gray
 Acquired: 1 October, 2002
 Price: $5
 Size: 1"
 Purity: <30%
 Sample Group: Powders
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