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Boron is not a high-profile element. Most people would probably be hard pressed to name an application of boron off the top of their heads. But it's actually fairly common: Borax (as in 20 Mule Team Borax) is hydrated sodium borate. Silly putty, an extremely complex and sophisticated molecular engineering job, uses boron cross-links to give it the critical property of being elastic on short time scales and inelastic on long time scales. This is not easy for a material to do, and boron is the key (see silly putty sample below).
Some very nasty boron compounds have also been used as rocket fuel, because they are able to pack more energy output into a smaller, lighter package than conventional fuels. Unfortunately the compounds in question also kill on contact with bare skin in a matter of seconds. So much for boring boron.
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Outrageous price quote.
Our first attempt at a boron sample involved Ed calling up a chemical supplier. They helpfully supplied a price quote of $2030 (two thousand and thirty dollars American) for one square inch of boron foil. We respectfully declined the offer. You might think that boron would be fairly inexpensive, given that it's dirt common and is the major component of things like Borax. But it turns out it's insanely difficult to fuse and work with, so formed shapes of it are quite unreasonably priced. We are preserving this price quote as a reminder of how much money can be saved by using eBay instead of chemical companies.
Source: Ed Pegg Jr
Contributor: Ed Pegg Jr
Acquired: 15 July, 2002
Price: $0/Nothing
Size: 1"
Purity: 0%
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 Very Odd Lump.
This is a strange-looking lump of solid pure boron. It has several different kinds of surfaces, as you can see if you click on the picture to see the large version. I would love to know more about the means by which this lump was made.
Reader Graham Cowan offers the following theory:From the bottom of p. 4 of this pdf file:"In 1985, Callery repurchased reserve pentaborane fuel from the military and reprocessed it into elemental boron. When this became unprofitable ..." Pentaborane, B5H9, is like all B-H compounds unstable with respect to dissociating into B and H2, so the only processing necessary would have been to heat it in the absence of air and water. (Probably in argon.)
Your nice big photo shows nodular surfaces and fracture ones. I think the nodular surface is where the gaseous BH stuff laid boron down on the hot lump.
--- Graham Cowan Here is his interesting page about boron as a fuel.
And as you can see below, this lump was considerably more cost effective than our first attempted sample.
Source: David Franco
Contributor: Ed Pegg Jr
Acquired: 16 August, 2002
Price: $12
Size: 0.5"
Purity: 99.9%
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Silly putty.
Silly putty contains about 4% boric acid, which is critically important for its bounce characteristic. See here for a reference.
Source: Ed Pegg Jr
Contributor: Ed Pegg Jr
Acquired: 10 December, 2002
Price: Donated
Size: 1"
Purity: 2%
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Sample from the Everest Element Set.
Up until the early 1990's a company in Russia sold a periodic table collection with element samples. At some point their American distributor sold off the remaining stock to a man who is now selling them on eBay. The samples (excepted gasses) weight about 0.25 grams each, and the whole set comes in a very nice wooden box with a printed periodic table in the lid.
To learn more about the set you can visit my page about element collecting for a general description and information about how to buy one, or you can see photographs of all the samples from the set displayed on my website in a periodic table layout or with bigger pictures in numerical order.
Source: Rob Accurso
Contributor: Rob Accurso
Acquired: 7 February, 2003
Price: Donated
Size: 0.2"
Purity: >99%
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