Calcium makes me think of chalk and orange juice. It's an essential nutrient: Your bones need calcium to grow and stay strong, and milk is a good source, hence the popularity of milk for children. So it might come as somewhat of a surprise to learn that calcium is a reactive alkali earth metal. It's not just a sort-of metal, it's an outright shiny, malleable, machinable metal. It has to be kept under oil or inert gas because it reacts with water (not violently like sodium, but fast enough that it won't last long in moist air). This still seems strange to me, even though I've seen (and hope to get soon) beautiful mirror-bright crystals of metallic calcium. The explanation of course is that you never see elemental calcium in nature: It exists only as things like calcium carbonate (limestone) and the like. 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 Minerals Samples with Rotatable Images Small lump 99.5%. 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: 99.5% 10 grams under oil. I'm hoping to get some really shiny crystalline calcium under argon soon, but this bottle has the advantage of being opened already, so if I want to do any experiments with the calcium, I can get to it without having to break a glass tube. Calcium is fairly reactive in air, so this bottle is filled with mineral oil, which has preserved a fairly clean surface on these metal chips. When I hear the word "calcium" I, and probably a lot of people, think of a chalky powder, like a calcium supplement pill. But that's a salt, like calcium carbonate (which is, in fact, chalk). Pure calcium really is a metal, lustrous, malleable, the works. Source: eBay seller flabster Contributor: Theodore Gray Acquired: 3 January, 2003 Price: $10.50 Size: 1" 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. For most sample from this set I have my own picture on the left and the one from the company here, but I haven't taken a picture of this sample yet so there's only one picture. 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% 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% Ulexite from Jensan Set. This sample represents boron in the "The Grand Tour of the Periodic Table" mineral collection from Jensan Scientifics. Visit my page about element collecting for a general description, or see photographs of all the samples from the set in a periodic table layout or with bigger pictures in numerical order. Source: Jensan Scientifics Contributor: Jensan Scientifics Acquired: 17 March, 2003 Price: Donated Size: 1" Composition: NaCaB5O6(OH)6.5H2O Apophyllite from Jensan Set. This sample represents oxygen in the "The Grand Tour of the Periodic Table" mineral collection from Jensan Scientifics. Visit my page about element collecting for a general description, or see photographs of all the samples from the set in a periodic table layout or with bigger pictures in numerical order. Source: Jensan Scientifics Contributor: Jensan Scientifics Acquired: 17 March, 2003 Price: Donated Size: 1" Composition: KCa4Si8O20(F,OH).8H2O + KCa4Si8O20(OH,F).8H2O Fluorite from Jensan Set. This sample represents fluorine in the "The Grand Tour of the Periodic Table" mineral collection from Jensan Scientifics. Visit my page about element collecting for a general description, or see photographs of all the samples from the set in a periodic table layout or with bigger pictures in numerical order. Source: Jensan Scientifics Contributor: Jensan Scientifics Acquired: 17 March, 2003 Price: Donated Size: 1" Composition: CaF2 Calcite from Jensan Set. This sample represents calcium in the "The Grand Tour of the Periodic Table" mineral collection from Jensan Scientifics. Visit my page about element collecting for a general description, or see photographs of all the samples from the set in a periodic table layout or with bigger pictures in numerical order. Source: Jensan Scientifics Contributor: Jensan Scientifics Acquired: 17 March, 2003 Price: Donated Size: 1" Composition: Ca(CO3)