  Less pure four pound lump.
This lump is the first stage in the purification of silicon for use in electronics. Quartz (typical sand, which is silicon dioxide) is chemically reduced to elemental silicon at high temperatures, yielding molten silicon which is then allowed to cool and solidify. This piece was from the top of the container so it shows one kind of surface on the top and quite a different kind where it was resting on other semi-molten blobs underneath. Contrast the relatively dull broken crystal surfaces of this 99.5% pure lump with the much shinier, crisper crystals of the 99.99+% lump above.
I chose this sample to represent its element in my Photographic Periodic Table Poster. The sample photograph includes text exactly as it appears in the poster, which you are encouraged to buy a copy of.
Source: eBay seller flabster
Contributor: Theodore Gray
Acquired: 10 January, 2004
Text Updated: 4 May, 2007
Price: $16
Size: 6"
Purity: >99.5%
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