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What is osmium (Os)? An overview of the rarest and densest precious metal in the world

When most people think of rare precious metals, they first think of gold, silver or platinum. However, the rarest and densest precious metal is osmium.

When most people think of rare precious metals, they first think of gold, silver or platinum. However, the rarest and densest (34 isotopes and 6 nuclear isomers are known) and heaviest metal is osmium (atomic number 76, abbreviated OS76, and 8th in the periodic table).

Osmium, a metal with a blue-white or steel-blue hue, is typically found alongside platinum in the Earth's crust and ranks high on the Mohs scale of hardness. With a hardness of 7 (diamond, for instance, is at 10), Osmium is not the hardest element but one of the hardest precious metals. Its resilience to high pressure is unparalleled among metals. The melting point of Osmium (Os76) exceeds 3000 degrees Celsius. This chemical element is utilized in medicine (implants), jewelry, and as an investment.

To illustrate Osmium's rarity: globally, only about 100 kg of Osmium is extracted annually from an approximate total yield of 1 ton. In contrast, several tons of gold are mined each year.

Compared to other precious metals like gold, Osmium was discovered relatively late. Along with another transition metal, Iridium, Osmium was identified in 1804 by British chemist Smithson Tennant after dissolving it in aqua regia. At the time, these two metals were considered impurities in platinum.

Fun Fact: The term "Osmium" (element symbol: Os) translates to "smell." The metal's name originates from its intense odor, which Tennant described as similar to radish and chlorine.

Osmium forms: Powder (osmium sponge), paste, crystal, disk, ingot, triangle, square, fused spheres, cube

Powdered raw osmium is considered toxic. For this reason, it must either be shaped into ingots, cubes, disks, squares or triangles or forced into crystalline form for further processing. In these forms, purified osmium is usually sold online and by stationary dealers as an investment product. However, investors are not advised to buy osmium in the form of osmium sponge (powder) or fused beads.

Osmium powder/sponge (raw osmium)

Raw osmium, i.e. the starting material for final processing steps, is available as a powder. Raw osmium, which is often sold online in this form, is known as "osmium sponge". Powdered raw osmium is sold in various online stores from around € 15, which looks like an attractive offer at first glance, especially for private investors and other buyers. However, caution is necessary here: raw osmium is considered highly toxic as it produces a harmful oxide. Osmium sponge also does not have its well-known steel-blue color but is black. Raw osmium is therefore entirely uninteresting for an investor. In fact, we strongly advise against buying osmium in powder form.

Osmium Paste

Processing osmium is considered particularly difficult because the precious metal is brittle. So how was the precious metal turned into filaments in OSRAM light bulbs? The electronics manufacturer employed a workaround: rather than pulling osmium into filaments, as is easily done with many other precious metals because of their lower melting points, they injected osmium as part of a paste into the necessary filaments. Naturally, this method of filament production, along with osmium itself (Os), was swiftly superseded by alternatives.

Osmium Crystals

Osmium crystals are the form most commonly used for emblazonment by the jewelry industry. Additionally, this is where osmium becomes interesting for investors. However, crystalline osmium is only formed during the so-called crystallization process. The atoms are brought into a crystalline structure, turning the once-toxic element Os76 (osmium) into a safe and valuable precious metal suitable for making jewelry or serving as an investment. The resulting crystal structure of osmium is exceptionally unique and exhibits a level of brilliance even surpassing that of diamonds. This remarkable quality is primarily attributed to osmium's ability to avoid light refraction.

Osmium Disks, Triangles and Squares

Osmium in disk (round), triangle, or square shapes essentially represents the forms into which osmium or osmium crystals can be crafted. It doesn't constitute a distinct category in itself. The predominantly flat shape lacks the organic impression of a pure osmium crystal, which may have aesthetic significance for some investors. However, as a disk, triangle, or square, the shaped osmium can be well-suited for further processing into jewelry.

Osmium bars

Some observers question the term "Osmium bar" (or Osmium ingot or Osmium bullion for that matter) as not entirely accurate because bars of other precious metals, such as gold or silver, are typically cast. However, due to osmium's extremely high melting point (over 3000 degrees Celsius), casting is not feasible. Consequently, osmium is not cast but rather pressed into bars. Osmium bars, along with osmium crystals, are considered popular investment options. Nevertheless, it's crucial to ensure that the osmium purchased, is purified osmium (Os), as is the case here with MetaMetals. Without purification, osmium would have almost no value to investors.

Osmium Cubes

In some cases, osmium is also sold as cubes. Similar to osmium ingots or osmium bars, the raw material is pressed to form it into a cubic shape. From an investor's perspective, there is generally nothing wrong with this, but it is again important to ensure that it is purified osmium. 

Osmium beads / fusion beads

Similar to osmium powder (osmium sponge), osmium beads are particularly inexpensive. This is because their production is comparatively simple. However, private investors are usually advised against buying osmium fusion beads, even if the seemingly low price is tempting. In contact with oxygen, the toxic gas "OsO4" can also form here. On the other hand, the tradability of osmium beads is questionable. Similar to osmium sponge, osmium fusion beads are sometimes used for osmium fraud, so offers should be carefully examined. These concerns are eliminated with the offered osmium products from MetaMetals: We provide certification and guarantee of a 99.95% purity level.

Liquid Osmium Tetroxide: Caution, do not confuse with pure osmium!

Osmium Tetroxide (OsO4) is – same as Osmium beads – not intended for acquisition by private individuals. Osmium tetroxide is available in either crystalline form or as a solution. It is a compound of the elements osmium and oxygen. You can already obtain 1g of Osmium tetroxide for a price slightly above €10. Element OsO4 (Osmium tetroxide) is used as a catalyst in chemistry, also has a strong radish-like odor, and is categorized in a high hazard class. Unlike osmium crystals or osmium bars, osmium tetroxide is also not suitable for investment.

Osmium is a platinum metal (along with platinum, palladium, iridium, rhodium, and ruthenium)

Platinum metals are characterized by their similarity in chemical properties and exceptionally high density. In total, six metals are classified as platinum metals: rhodium, iridium, palladium, platinum, ruthenium, and osmium. These six platinum metals were formerly referred to as the platinum group, which was technically an inaccuracy. This is because even the elements palladium, nickel, and platinum are referred to as the 'platinum group,' although they occupy a different position in the periodic table.

Production and Extraction of Osmium (Element Symbol: Os)

Both the production and extraction of osmium are intricate processes, partly responsible for its high price. While other precious metals like gold or silver can be mined, the extraction of osmium goes beyond this single method. Typically, osmium is obtained from ores that contain precious metals, as well as from anode sludge (a byproduct in metal production). Aqua regia, which is an acid composed of hydrochloric acid and nitric acid, is used to dissolve precious metals such as palladium, gold, and platinum from the ore. Consequently, this chemical process leaves silver and the platinum group metals, to which osmium belongs, behind.

In a subsequent step, silver is dissolved, leaving only the platinum group metals (rhodium, iridium, palladium, platinum, ruthenium, and osmium). Rhodium is then separated, followed by the separation of ruthenium and osmium in successive steps. However, the process does not conclude at this stage. Osmium is further reduced to metallic osmium. In this form, osmium can be further processed and ultimately utilized. If this sounds complex, you are correct! This complexity helps explain why osmium is so valuable, rare, and, above all, expensive.

What is osmium used for? Use of osmium and osmium tetroxide in medicine, jewelry, and as an investment

Although osmium is used in a variety of ways, it is not quite as widely used as other precious metals such as gold, platinum or silver. This is because osmium is considered toxic in its original form. Only after further processing, such as purification or crystallization, is osmium considered harmless and is used for alloys, implants, jewelry and as an investment. The best-known compound, osmium tetroxide, is used in cell membranes and fats in forensics, but also in electronic microscopy for contrast enhancement and fixation, for example.

Osmium as jewelry (rings, necklaces, ...)

The fact that osmium is now increasingly being used by the jewelry industry to make rings, osmium necklaces and other jewelry may sound unusual to some people at first. However, osmium actually sparkles more than diamonds and is much rarer than gold, silver or platinum, which is why osmium has become increasingly attractive in recent years. Osmium is also considered a forgery-proof and wear-resistant precious metal, which makes it a competitor to diamond jewelry.

Use of osmium in medical implants, alloys, the chemical industry and electronics

Osmium is often used in the medical field for implants or artificial heart valves. Due to the extremely high density of osmium, the rare precious metal is used to produce very hard alloys for fountain pen tips, needles or electrical contacts. Osmium also acts as a catalyst for hydrogenation in the chemical industry.

In the past, osmium was also used by the light bulb manufacturer OSRAM for the production of light bulbs, but this is no longer done today.

Osmium as an investment

Primarily due to its rarity and costly production, osmium is popular with investors, not least as an investment. As with all other forms of use, however, it is only available in purified form, usually as a pressed bar or crystal (optionally on geometric carrier materials).

What makes osmium so expensive?

Several properties and factors come together in the case of osmium, that make the transition metal one of the most expensive precious metals in the world. 

Firstly, osmium is incredibly rare. To put it in perspective: Osmium is around 1500 times rarer than gold.

Secondly, the complex processing of raw osmium results in high costs. Due to its toxicity, for example, osmium must first be converted into crystalline form. However, other forms are also common, especially for investment purposes, such as bars, disks or cubes.

Osmium price: Is osmium or gold more expensive?

There is no general answer as to whether osmium or gold is more expensive. It depends on the degree of purity or the crystallization process of the osmium. Osmium in its unpurified form is cheaper than gold. However, crystalline osmium, for example, is far more expensive and therefore more valuable than gold. 

Does osmium have a future?

Osmium (element: Os) is a precious metal that was discovered  just over 200 years ago. This makes it one of the younger members of the periodic table, but also a metal with great potential for the future.

One reason why osmium has so far led a niche existence was its complicated processing. This only changed less than 10 years ago with the crystallization process, which brought osmium further into the mainstream.

However, it is precisely this short history that makes osmium an interesting investment for many investors. This is also reflected in the price of osmium, which was still around € 500 per gram (g) in 2018, but had already climbed to over € 1200 per gram by 2023

Buying osmium

Osmium is usually sold online by various dealers as osmium crystal (either as a disk, triangle or square) or as osmium bars for use as an investment.

As mentioned above, there are a few things to watch out for when buying or trading osmium. Raw osmium in powder form or even as melting balls/Osmium beads may seem cheap to the inexperienced buyer, but they are highly toxic and should not be purchased in this form. Only purified osmium has the value that is of interest to an investor. It is also important to only purchase osmium from trustworthy suppliers such as MetaMetals, as otherwise the risk of fraud is high.