Precious Metals Series

All About Osmium

Ever heard of osmium? You will most likely hear more and more about this element due to its increasing popularity in every application. One of the densest elements in the world, osmium is a bluish, hard, lustrous metal and even at high temperatures, can be brittle.  Part of the group of platinum, osmium has the lowest vapor pressure and the highest melting point. One highly toxic oxidizing agent that is very powerful is osmium tetroxide.

Nickel refining’s by product is osmium. This element occurs in the iridosule mineral and in river sands that bear platinum in South America, North America and the Urals. While there is little osmium anywhere else, processed nickel ores product a lot of osmium.

Osmium Uses

Osmium is usually alloyed with other precious metals due to how dense it is. This is used for making products such as electrical contacts, phonograph needles and instrument pivots. When combined naturally with iridium, osmium is used in the tips of fountain pen.

History

Discovered in London, England in 1803, Osmium was intertwined with the discovery of other platinum group metals. It reached Europe as a small silver platina, first encountered in silver mines in the late seventeenth century around Colombia’s Choco Department. When they discovered that this metal was not one of the alloys, but a new element distinctly, it was published in 1748. Platinum researchers dissolved it to create soluble salts in aqua regia. They also observed smaller amounts of an insoluble, dark residue. They first assumed that osmium was graphite. Later, more analysis was done and the conclusion was that it contained a new metal. The powder was alternately treated with acids and alkali. A new oxide, volatile, was created. Vauquelin believed that this is a new metal. The research was continued by Tennant who had larger amounts of residue. He named it osmium since the smoky, ashy smell reminded him of the Greek word “osme.”

In the Haber process, osmium and uranium were early successful catalysts. Ammonia was produced by the nitrogen fixation reacting to hydrogen and nitrogen. This gave enough yield to create a process that was successful, economically. In 1908, catalysts that were cheaper based on iron oxides and iron were introduced to first pilot plants by the same group.  This removed the need for rare, expensive osmium. These days, osmium is primarily obtained from the processing of nickel and platinum ores.

Osmium Applications

Due to the extreme toxicity and volatility of the oxide, osmium is hardly used in a state that is absolutely pure. However, it is alloyed often with other metals. Alloys such as these are used in applications of high wear. Alloys of osmium such as osmiridium are quite hard and along with other metals in the platinum group, these are used for fountain-pen tips. This is also used for electrical contacts and instrument pivots, as these can resist getting worn down even with frequent operations. These were also used for phonography styli tips around the record era.