Selenium used to be used in rectifiers, before the development of semiconductor-based diodes. They were big old things that didn't work very well (see picture below). These days selenium is in the news primarily when some place gets too much of it in the soil or water (either naturally or as a result of industrial dumping). People or animals eating plants grown in such soil can develop serious medical problems. On the other hand, selenium is also an essential nutrient with a minimum recommended level of 50mcg/day. It's all a question of quantity. Detailed Technical Data Compare at other websites: www.webelements.com Los Alamos National Labs Royal Society of Chemistry Toxicology Isotope information Minerals Translations and Etymology Science Fiction (Main Site) Comics Poetry (Main Site) Haiku (Main Site) Collections: Elements in the Human Body Elements with External Samples Samples with Rotatable Images Small button 99.999%. Kindly donated by David Franco, who sent many elements after seeing the slashdot discussion. Source: David Franco Contributor: David Franco Acquired: 17 May, 2002 Price: Donated Size: 0.1" Purity: 99.999% Rectifier. Before the invention of silicon and germanium rectifiers, these were state of the art. Despite being called "miniature" rectifiers, they are huge by current standards! Source: Charles Cowie Contributor: Charles Cowie Acquired: 9 September, 2002 Price: Donated Size: 2.5" Purity: >90% Lumps. These are smooth lumps that look like they've been melted. Click the source link for an interesting story about where this sample came from. Source: Tryggvi Emilsson and Timothy Brumleve Contributor: Tryggvi Emilsson and Timothy Brumleve Acquired: 6 September, 2002 Price: Donated Size: 0.75" Purity: >99% Hunks. These are bigger hunks of selenium from Canada, about 20 grams each. They are nondescript as elements, but do illustrate what a wonderful place eBay is to deal with. The first one failed to arrive after a while, so I emailed the seller asking if it had been sent. He assured me it had, but offered to send another if it didn't arrive soon. It didn't, and he did. Naturally not long after that, the first one arrived in a torn, dirty envelope postmarked almost a month before that looked like it had been opened, but still contained its lump. The replacement arrived the next day. People on eBay are just the nicest people you'd ever want to meet. Source: eBay seller kingendymion Contributor: Theodore Gray Acquired: 27 September, 2002 Price: $26 Size: 1.5" Purity: >99% Sample from the Red Green and Blue Company Element Set. The Red Green and Blue company in England sells a very nice element collection in several versions. Max Whitby, the director of the company, very kindly donated a complete set to the periodic table table. 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 The Red Green & Blue Company Contributor: Max Whitby of The Red Green & Blue Company Acquired: 25 January, 2003 Price: Donated Size: 0.2" Purity: 99.5% 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% Native selenium. (External Sample) Huge lump of elemental selenium, naturally occurring. Location: The Harvard Museum of Natural History Photographed: 2 October, 2002 Size: 18 Purity: >90%