| | |   Zinc medallion. For a Popular Science column I wrote about making glass I needed a graphite mold to press the glass into.  I machined one out of a block of graphite, and tested it by casting this medallion out of cheap and easy to melt zinc.  Satisfied with the shape I went on to make similar medallions out of glass (listed under silicon because glass is mostly silica).
 Source: Theodore Gray
 Contributor: Theodore Gray
 Acquired: 26 October, 2008
 Text Updated: 29 January, 2009
 Price: $1
 Size: 2.5"
 Purity: 99.9%
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