Iridium
Iridium
Rhenium Osmium Iridium Platinum Gold Blank Blank Blank Blank Cobalt Rhodium Iridium Meitnerium
Iridium Spark PlugIridium Real iridiumIridium Sample from the Everest Set
Iridium Larger lumpIridium Phonograph needleIridium Museum-grade sample
Iridium Ion sourceIridium K-T Boundary ClayIridium Osmiridium aka Iridosmine
Iridium Big bag of beadsIridium Photo Card Deck of the ElementsIridium Ad for osmiridium tipped pen
Iridium Osmiridium penIridium Osmiridium penIridium
Iridium Iridium Iridium
Iridium
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Osmium and Iridium are the two most dense elements in pure form. They are also very pretty metals, iridium particularly. Unlike osmium, iridium does not tarnish in air, and is in fact impervious to many forms of chemical attack, much like platinum. An alloy of 90% platinum and 10% iridium is widely used in both the jewelry and chemical industries, because it is strong, hard, beautiful, and impervious to almost all chemicals even at very high temperatures.

Which is the most dense element, osmium or iridium? That honor has changed hands a couple of times over the years. How, you might ask? Because measuring the density of a pure element isn't nearly as straightforward as you might think. For one thing, it can be different for different crystalline forms (allotropes) of the same element. For example, diamond is much denser than graphite: Which is the true density of carbon? Both. In the case of metals, it may be impossible to grow single crystals, so you're measuring the density of a polycrystalline mixture, and the density may depend on details of how the material cooled. Minute impurities can also have a big impact on the density.

So, as measurements and purities were refined over the years, the current best values of osmium and iridium kept changing, and that's how they traded places as most dense of all. I solved this dilemma by only having room to engrave three decimals places of the density, and to three decimal places their density is identical, so I didn't have to pick sides.
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Samples with Stories
Iridium Spark Plug
3D3DSpark Plug.
People make spark plugs out of the craziest elements, like Polonium. Iridium probably makes a certain amount of sense, because it's likely to survive a long time under harsh conditions. Whether it's much advantage over platinum I wouldn't know.
Here's an interesting article about different elements in spark plugs.
Amusingly, I purchased a 2004 model Toyota Sienna minivan (kids, you know) and the owners manual is very firm that one must use only iridium spark plugs in this vehicle. What, platinum is not good enough?
Source: eBay seller accurateimage
Contributor: Theodore Gray
Acquired: 31 July, 2002
Text Updated: 11 August, 2007
Price: $18
Size: 3"
Purity: >90%
Sample Group: Spark Plugs
Iridium Real iridium
3DReal iridium.
Iridium metal is hard to get, and very expensive. In fact, it was in the very last group of elements I was able to acquire to complete my collection. It was donated by the extremely kind Max Whitby of the The Red Green & Blue Company, which sells a complete collection of elements.

Osmium and Iridium are the two densest elements in the world (they are in fact so close in density that which one is considered the densest has switched a couple of times over the years). Even though this is a quite small lump, you can feel its weight when you shake the bottle: Quite surprising. Having a large block of this would be remarkable, but the closest I'm likely to come to that is my large blocks and cylinders of tungsten, which are only about 15% less dense.

To learn more about the set you can visit my page about element collecting for a general description or the company's website which includes many photographs and pricing details. I have two photographs of each sample from the set: One taken by me and one from the company. You can see photographs of all the samples displayed in a periodic table format: my pictures or their pictures. Or you can see both side-by-side with bigger pictures in numerical order.

The picture on the left was taken by me. Here is the company's version (there is some variation between sets, so the pictures sometimes show different variations of the samples):


Source: Max Whitby of RGB
Contributor: Max Whitby of RGB
Acquired: 20 January, 2003
Text Updated: 11 August, 2007
Price: Donated
Size: 0.2"
Purity: 99.95%
Iridium Sample from the Everest Set
Sample from the Everest Set.
Up until the early 1990's a company in Russia sold a periodic table collection with element samples. At some point their American distributor sold off the remaining stock to a man who is now selling them on eBay. The samples (except gases) weigh about 0.25 grams each, and the whole set comes in a very nice wooden box with a printed periodic table in the lid.

To learn more about the set you can visit my page about element collecting for a general description and information about how to buy one, or you can see photographs of all the samples from the set displayed on my website in a periodic table layout or with bigger pictures in numerical order.

Source: Rob Accurso
Contributor: Rob Accurso
Acquired: 7 February, 2003
Text Updated: 29 January, 2009
Price: Donated
Size: 0.2"
Purity: >99%
Iridium Larger lump
3D3DLarger lump.
This lump is similar to, but larger than, the samples in the The Red Green & Blue Company's, element collection.

I chose this sample to represent its element in my Photographic Periodic Table Poster. The sample photograph includes text exactly as it appears in the poster, which you are encouraged to buy a copy of.
Periodic Table Poster

Source: Max Whitby of RGB
Contributor: Max Whitby of RGB
Acquired: 20 February, 2003
Text Updated: 11 August, 2007
Price: Donated
Size: 0.5"
Purity: 99%
Iridium Phonograph needle
Phonograph needle.
Osmium phonograph needles are fairly common, but this is the first iridium one I've seen. Hard metals were used for needles like this so they would last a long time playing abrasive records.
Source: eBay seller harrymarks
Contributor: Theodore Gray
Acquired: 29 September, 2003
Price: $5
Size: 0.5"
Purity: <50%
Iridium Museum-grade sample
3DMuseum-grade sample.
In early 2004 Max Whitby and I started selling individual element samples identical or similar to the samples we use in the museum displays we build. These are top-quality samples presented in attractive forms appropriate to the particular element. They are for sale from Max's website and also on eBay where you will find an ever-changing selection of samples (click the link to see the current listings).
This bottle contains about 50 grams of arc-melted buttons made in Max's reduced-pressure argon-arc furnace.
Source: Theodore Gray
Contributor: Theodore Gray
Acquired: 24 February, 2004
Text Updated: 11 August, 2007
Price: See Listing
Size: 2"
Purity: >99%
Sample Group: RGB Samples
Iridium Ion source
3D3DIon source.
This was described as a "Varian 0981-82850-302 Thoria / Iridium Ion Source". Whether this means it contains thoria (a name for thorium oxide) and/or iridium I'm not clear. I'm also not clear whether it's meant to emit iridium ions, or other kinds of ions with the iridium being the material out of which some component of it is made. I think probably the latter. It looks like all plain metal to me, but I could be mistaken. In any case, it's a fascinating bit of tangled metal obviously intended to be used inside a vacuum chamber to emit some kind of ions, and it probably contains some iridium, which makes it good enough for me to list.
Source: eBay seller dougcarol1987
Contributor: Theodore Gray
Acquired: 11 June, 2005
Text Updated: 31 May, 2006
Price: $16
Size: 3"
Purity: 0%
Iridium K-T Boundary Clay
3D3DK-T Boundary Clay.
The K-T boundary clay is is found in thin layers all over the world at sedimentary levels that indicate it is the same age everywhere: About 65 million years ago. This is the boundary between the Cretaceous (K for some reason) and the Tertiary (T for obvious reasons) periods, and also the time at which there was a mass extinction.

That such a thin layer of similar material should be found all over the globe is strange, but what's even stranger is that it is always highly enriched in iridium compared everything around it. It's as if something dumped a huge quantity of iridium on the earth and spread it around in some kind of giant explosion.

That something was almost certainly a large (ca. 10km diameter) chondritic meteorite, a type known to contain very high levels of iridium compared to the earths crust. All the evidence points to such an object hitting the Yucatan peninsula of Mexico a the same time the clay was deposited and the dinosaurs became extinct.

And the dark layer in this rock is a tiny bit of that iridium-rich clay material.

Source: Jensan Scientifics
Contributor: Theodore Gray
Acquired: 8 April, 2009
Text Updated: 9 April, 2009
Price: Anonymous
Size: 1.5"
Purity: <1%
Iridium Osmiridium aka Iridosmine
3D3DOsmiridium (aka Iridosmine).
These are very small granules of native (naturally occurring) osmium-iridium alloy. These two metals are often found combined this way, and because the alloy is actually in many ways more useful than either element on its own, the mixture is often used just as it's found, for example in the tips of expensive fountain pens. Don't be fooled by the picture: This stuff is about the size of fine sand, I've just got a really good macro lens.
Source: eBay seller entropydave
Contributor: Theodore Gray
Acquired: 15 February, 2006
Text Updated: 5 December, 2006
Price: $85
Size: 0.02"
Composition: IrOs
Iridium Big bag of beads
3D3DBig bag of beads. (External Sample)
This is a large ($18,000) order of platinum group metals placed by an excellent customer of my partner Max Whitby's element sales business. I happened to be visiting Max in London just before the order needed to be shipped to our customer in the US, so I hand-carried the precious cargo home rather than risking international shipping. These beads were made by Max in his reduced pressure argon arc furnace.

The customer wishes to remain anonymous, so you'll just have to keep wondering where this remarkable trove of rare metals currently resides: The only thing you can be sure of is that I don't have it.
Source: Max Whitby of RGB
Contributor: Max Whitby of RGB
Acquired: 4 September, 2007
Text Updated: 7 September, 2007
Price: N/A
Size: 0.25"
Composition: ReRuOsIr
Iridium Photo Card Deck of the Elements
3D3DPhoto Card Deck of the Elements.
In late 2006 I published a photo periodic table and it's been selling well enough to encourage me to make new products. This one is a particularly neat one: A complete card deck of the elements with one big five-inch (12.7cm) square card for every element. If you like this site and all the pictures on it, you'll love this card deck. And of course if you're wondering what pays for all the pictures and the internet bandwidth to let you look at them, the answer is people buying my posters and cards decks. Hint hint.
Source: Theodore Gray
Contributor: Theodore Gray
Acquired: 19 November, 2008
Text Updated: 21 November, 2008
Price: $35
Size: 5"
Composition: HHeLiBeBCNOFNeNaMg AlSiPSClArKCaScTiVCrMn FeCoNiCuZnGaGeAsSeBrKr RbSrYZrNbMoTcRuRhPdAg CdInSnSbTeIXeCsBaLaCePr NdPmSmEuGdTbDyHoErTm YbLuHfTaWReOsIrPtAuHgTl PbBiPoAtRnFrRaAcThPaUNp PuAmCmBkCfEsFmMdNoLrRf DbSgBhHsMtDsRgUubUutUuq UupUuhUusUuo
Iridium Ad for osmiridium tipped pen
Ad for osmiridium tipped pen.
A magazine ad for an osmiridium-tipped fountain pen.
Source: eBay seller mirluck
Contributor: Theodore Gray
Acquired: 25 April, 2009
Text Updated: 27 April, 2009
Price: $5
Size: 10"
Composition: OsIr
Iridium Osmiridium pen
3D3DOsmiridium pen.
Osimiridium is a naturally occurring mixture of osmium and iridium. It's a very hard metal used in the tips of fountain pens.
Source: eBay seller tbagkdr
Contributor: Theodore Gray
Acquired: 13 January, 2010
Text Updated: 13 January, 2010
Price: $30
Size: 1"
Composition: OsIr
Iridium Osmiridium pen
3D3DOsmiridium pen.
Osimiridium is a naturally occurring mixture of osmium and iridium. It's a very hard metal used in the tips of fountain pens.
Source: eBay seller tbagkdr
Contributor: Theodore Gray
Acquired: 13 January, 2010
Text Updated: 13 January, 2010
Price: $30
Size: 1"
Composition: OsIr
Iridium Iridosmine
Iridosmine. (External Sample)
Naturally occurring alloy of iridium and osmium.
Location: The Harvard Museum of Natural History
Photographed: 2 October, 2002
Size: 1
Purity: 50%
Iridium Native iridium
Native iridium. (External Sample)
Natural iridium nugget.
Location: The Harvard Museum of Natural History
Photographed: 2 October, 2002
Size: 1
Purity: >90%
Iridium Oliver Sacks' slab
Story3DOliver Sacks' slab. (External Sample)
This iridium was original sold to Sacks by my friend Max Whitby in the form of marble-sized buttons. Sacks wanted it in the form of a single large slab, and in the summer of 2004 I got a chance to visit Kaistar R&D in New Jersey with him. Kaistar is run by a family of Russians and they have the lovely electron-beam furnace you see here, with Sacks in front of it holding his newly minted 1.7 pound lump of solid high-purity iridium. Read my story about the trip for more information and pictures of what goes on inside the furnace.
Location: Oliver Sacks' Office
Photographed: 6 August, 2004
Size: 2.5
Purity: 99.995%
Iridium Big bag of beads
3D3DBig bag of beads. (External Sample)
This is part of a large ($18,000) order of platinum group metals placed by an excellent customer of my partner Max Whitby's element sales business. I happened to be visiting Max in London just before the order needed to be shipped to our customer in the US, so I hand-carried the precious cargo home rather than risking international shipping. These beads are made by Max in his reduced pressure argon arc furnace.

The order consisted of equal volumes of ruthenium, rhenium, osmium, and iridium. Here is what the whole collection looks like:


The customer wishes to remain anonymous, so you'll just have to keep wondering where this remarkable trove of rare metals currently resides: The only thing you can be sure of is that I don't have it.
Location: Anonymous
Photographed: 4 September, 2007
Text Updated: 6 September, 2007
Size: 0.25"
Purity: 99.99%
Iridium Big bag of beads
3D3DBig bag of beads. (External Sample)
Close-up of one bead from the previous sample.
Location: Anonymous
Photographed: 4 September, 2007
Text Updated: 6 September, 2007
Size: 0.25"
Purity: 99.99%
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