about Osmium » Occurrence
General sources such as Wikipedia provide figures such as the assumed proportion of osmium in the earth's crust of 1 - 10-8 parts. Even then, osmium would be extremely rare. However, the figures are extrapolated and are therefore less accurate the rarer a metal is. However, osmium is usually associated with the other platinum metals ruthenium, rhodium, iridium, palladium and platinum. For this reason, sample calculations can be made to better define the quantities of osmium.
The Osmium World Council publishes the latest figures in its annual report. These figures can be found at www.osmium-world-council.com. Conclusive figures for osmium’s occurrence in the earth’s crust and in circulation are difficult to calculate because countries like China treats such information as state secrets. The information provided by current manufacturers and refineries is also highly volatile and partly speculative. For this reason, the figures given are never exact, but are highly indicative. In recent years, however, the assumptions of real reserves and real available quantities of raw osmium have followed a clear downward trend.
Osmium deposits are divided into resources and reserves. In other words, the deposits are defined by how much osmium is predicted to be contained within a mine, and how much osmium has been confirmed to be actually minable. However, the presence of osmium in a mine does not guarantee that it will be separated from the ores once extracted. If the occurrence of osmium in the extracted ores is too low, extraction is not economically viable. For thousands of tons of ore, there are often only a few grams of raw osmium, which are also highly impure. The challenge for the osmium market is the purification to extreme qualities in the range of 7N in order to make osmium crystallizable and thus suitable for its main application in the investment and jewelry market.
Osmium occurs naturally in thin platelets, but also bound as selenide, sulfide or telluride. In the process of separation from other metals, it is usually lost in the flue gas under the oxygen supply in the process of the separation from other metals and is released into the atmosphere. These quantities are irretrievably lost, although they are included in the reserves at the deposits. As a result, the rarest non-radioactive metal in the world becomes even more rare.
In general, there are various deposits of osmium, which are divided into primary and secondary deposits. Primary deposits are distributed internationally and contain copper as the main metal, as well as nickel and occasionally chromium and iron. Very small quantities of platinum metals are bound here. However, this does not mean that they will be extracted, and in the process of separating the industrial metals they are often not separated because of their small proportions. Isolated deposits of osmium ore one could with for, do not exist. Parts of the osmium deposits originate from the rhenium decay series, are associated with the platinum metals in mines or originate from the impacts of extraterrestrial objects in the early days of the Earth.
In addition to the known ores, there are secondary placer deposits in which osmium and, above all, the other platinum metals occur in traces. The metals were washed out by water after weathering and have been deposited in placers like gold due to their density. The natural alloy osmiridium or too, depending on the proportion of osmium, iridosmium, is found here.
The most important deposits are the platinum metal-rich nickel ores in Canada (Sudbury, Ontario), Russia (Ural) and South Africa (Witwatersrand). Secondary deposits are less significant and can be found geographically in the Urals, throughout South America, throughout Africa, and in Indonesia.
