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Hafnium is a beautiful metal, just beautiful. It's also very useful, because it likes to give up electrons to the air around it. For that reason it's very good for starting an electric arc, for example in a plasma cutting torch (see below). I'm sort of surprised it isn't used in spark plugs, considering how many other elements are.
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 Plasma cutter electrode.
Plasma cutters are really neat: You can cut thick steel using nothing but electricity and air. No acetylene, no fuel of any sort, just the iron burning in air. Jim uses one on our farm to make metal art. Here's a picture of the arc plasma as it's reaching out to the metal, a fraction of a second before the metal ignites:
Here it is just after the metal ignites:
The sound for this sample is the sound of this plasma torch: The quieter sound at the start is the sound of the compressed air blowing out of the tip before the arc starts. Then it ignites and becomes much louder, and towards the end shuts off again leaving just the air sound.
Oh, wait, I guess I should explain what this has to do with hafnium! Ed found out that in the center of the electrode for just about any air-based plasma torch there is a small button of hafnium! Very strange where you find these elements. I think the ones in our torch have such a button, but they are chrome colored and it's hard to see. I went to my favorite welding shop and asked to pick out one where the dot was most prominent. This one shows a nice color contrast. I had planned to pay for the tip, but I guess he thought it was such a strange request he'd just give it to me.
Source: Claudin Welding Supply
Contributor: Claudin Welding Supply
Acquired: 24 July, 2002
Price: Donated
Size: 1"
Purity: >90%
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 Heavy 290g lump.
This lump has one of the most interested surfaces I've seen. Smooth, silky, yet crystalline. It's very heavy (heavier than lead, though not in the same league as tungsten). Words don't do justice to this very interesting hunk of metal. Gillian Pearce, the source, reports that this surface is very characteristic of hafnium, and forms spontaneously any time hafnium metal is cooled from a molten state. I'd sure like to see that happening some day, but the extremely high melting point means it's not something I can do at home.
The rotatable 3D image is particularly good for this sample: Worth the download time. You'll see that the back face is completely different than the front face you see in the main picture.
Analysis by x-ray fluorescence spectroscopy at the Center for Microanalysis of Materials, University of Illinois (partially supported by the U.S. Department of Energy under grant DEFG02-91-ER45439) indicates it is 99.25% hafnium, 0.75% zirconium. Hafnium and zirconium are quite difficult to separate, and even very pure zirconium is often sold with the understanding that there is several percent of hafnium contamination, and vice versa. Since they are chemically very similar (which is why they are hard to separate) this is often not a big deal, other than in nuclear applications.
Source: eBay seller rubbleshop
Contributor: Theodore Gray
Acquired: 19 October, 2002
Price: $18
Size: 2"
Purity: 99.25%
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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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