Hafnium metal ingot - one troy ounce - .988 bullion Discovered by Dirk Coster and Gyorgy Hevesy in 1923 and named Hafnia (that Latin name for Copenhagen, where it was discovered) hafnium is a dense, corrosion resistant, high melting point metal. These properties along with the high affinity of its nuclei to absorb thermal neutrons makes it ideal for use in nuclear reactor control rods (i.e. it is used to control the rate of nuclear reactions by absorbing radioactive particles, though itself is not radioactive). The nuclear industry which is expected to continue to ramp back up in coming years after the 2011 Fukushima disaster, as reactors are restarted and more are planned is the largest user of hafnium though it is also used in the semiconductor industry and its superalloys (along with niobium, tungsten or titanium) are used in the aerospace industry. Hafnium is relatively rare with an average estimated concentration in the Earth's crust of 5.8 parts per million. Worldwide annual production is not well known, but is estimated between 70 and 80 tonnes compared with over 3000 tonnes of gold mined each year. Inscribed on our ingots are the chemical symbol (Hf), purity (98.8%), weight (one troy ounce), and a serial number (this number is unique and will vary). On the reverse is our logo. Hafnium and zirconium occur naturally together and are very difficult to completely separate, accounting for the slightly lower purity of these ingots compared with our other metals. The purity of our previous batch of hafnium was similar to this though we included the (Hf+Zr) designation on the assay cards of the previous batch as is commonly done with these sister metals, and of course explained it in the product description. For the current batch we chose to list the purity of the hafnium metal only. These ingots are fairly well polished but do have light swirl marks, similar to the one pictured. There can be tiny edge dings and other tiny imperfections which do not detract from the inherent value of this rare industrial metal. As always, weight and purity are guaranteed by Rare World Metals Mint. Hafnium is not known to be toxic and the solid form we supply is considered safe. Fine turnings or particles of hafnium are pyrophoric (can spontaneously ignite) so please handle with care. Please also keep in a safe place, do not ingest, and keep out of the reach of children. Each ingot will be shipped with an assay certificate and every shipment will include our velvet logo bag. If you are not completely satisfied with any purchase from us, you have 30 days to return it for a full refund (buyer to pay return shipping). Domestic shipping is free for all orders over $199 (enter code free shipping at checkout). For orders of $199 or under, domestic shipping is $9.95. International shipping is via DHL, FedEx, or USPS international express and costs $45 for shipments up to a pound (9 one ounce ingots or less including packaging materials) and $10 for each additional pound. International customers please be aware that your country may levy import duties and/or VAT taxes on your purchase from us. We have nothing to do with this and cannot pay it for you. If you refuse our package because of this extra cost we will take it back and will refund your order in full once received minus the cost of the return shipping. If you are unsure what these import costs will be please check with your country's customs office. Please see our blog on hafnium and its "alter ego" metal zirconium (to emerge in the coming months): http://www.rwmmint.com/blogs/news/14929137-dr-jekyll-and-mr-hyde http://en.wikipedia.org/wiki/Hafnium http://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth%27s_crust
