Hafnium metal bar - various weights available - .992 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 these bars are the chemical symbol (Hf), purity (99.2%), weight (various as marked), a serial number (this number is unique and will vary), and 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. These bars are fairly well polished but do have light residual cut marks and occasional scratches, similar to the ones pictured. There can also be tiny edge dings and chips. These imperfections do not detract from the inherent value of this rare industrial metal. These bars were all cut from a cast wedge shaped block of hafnium that was sourced from Australia. Most are rectangular in shape though some are more trapezoidal and one is more triangular. Several retain a surface from the original block that hasn't been cut or polished. 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 bar 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 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
