This absolutely stunning precision-machined bar of solid rhenium is worth a pretty serious amount of money, though Max got a great deal on it on eBay. Its density is around 20.5g/cc, slightly less than the theoretical density of 21.0g/cc. It's common for large bars of very high melting point metals like this to be lower in density than they should be, because they are formed by sintering a fine powder of the metal under high pressure (casting such a large piece being virtually impossible). The sintering process leaves microscopic voids, which must be compressed out by hammering, swaging, and the like in an attempt to beat the metal to the highest possible density.
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: Max Whitby of RGB
Contributor: Theodore Gray
Acquired: 24 February, 2004
Text Updated: 4 May, 2007