Osmium metal is hard to get, and very expensive. In fact, it was in the very last group of elements I was able to acquire to complete my collection. It was donated by the extremely kind Max Whitby of the The Red Green & Blue Company, which sells a complete collection of elements (including this one).
Osmium and Iridium are the two densest elements in the world (they are in fact so close in density that which one is considered the densest has switched a couple of times over the years). Even though this is a quite small lump, you can feel its weight when you shake the bottle: Quite surprising. Having a large block of this would be remarkable, but the closest I'm likely to come to that is my large blocks and cylinders of tungsten, which are only about 15% less dense.
To learn more about the set you can visit my page about element collecting for a general description or the company's website which includes many photographs and pricing details. I have two photographs of each sample from the set: One taken by me and one from the company. You can see photographs of all the samples displayed in a periodic table format: my pictures or their pictures. Or you can see both side-by-side with bigger pictures in numerical order.
The picture on the left was taken by me. Here is the company's version (there is some variation between sets, so the pictures sometimes show different variations of the samples):
Source: Max Whitby of RGB
Contributor: Max Whitby of RGB
Acquired: 20 January, 2003
Text Updated: 11 August, 2007