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To save people some time clicking through... A 10mm cube of Iridium weighs ~21.9g. And from this source, costs $9000. From the same source, a single gram is o

To save people some time clicking through... A 10mm cube of Iridium weighs ~21.9g. And from this source, costs $9000. From the same source, a single gram is only $275. This means that due to the difficulty in working with this very dense metal, the cost of turning the Iridium into a cube is nearly $3000 (on top of the ~$6000 for the metal itself)!

tyingq 5y ago
Osmium would be heavier still (22.59 grams/cc), and a relative bargain at $1275 for the 10mm cube at the same source. Not polished/shiny though.
- TeMPOraL 5y ago
  And, as divbzero's Quora link points out, it's going to kill you by oxidizing into a toxin when exposed to open air.
  - tyingq 5y ago
    That seems to be a concern with osmium powder, ground osmium, etc. I don't think that a cube has any handling requirements more exotic than lead solder.
    - GravitasFailure 5y ago
      Less than that even. It's a noble metal and doesn't like to react under normal conditions, though hitting it with a blowtorch might ruin your day.
- adrian_b 5y ago
  Osmium is the densest pure metal, but iridium has an almost identical density, i.e. 22.56 for Ir, vs. 22.59 for Os. The difference is far too small to give you a different feeling when holding a piece of either osmium or iridium. While osmium and iridium are the densest pure metals, there is a range of composition in the osmium-iridium alloys which has a slightly greater density than both pure osmium and pure iridium. That happens because the atomic concentration of Os is a little higher than that of Ir while the atomic mass of Ir is a little higher than that of Os. While increasing the proportion of Ir in an Os-Ir alloy from 0% to 100%, there is a range where the atomic concentration decreases slower than the average atomic mass increases, so the density of the alloy becomes greater than the density of pure osmium. At higher Ir percentages, the increase in atomic volume overcomes the increase in atomic mass, so the density becomes a little lower than for pure Os. Unlike pure osmium, an Os-Ir alloy would not be dangerous to handle. Pure osmium is slowly oxidized in air releasing the volatile and extremely dangerous osmium tetraoxide. In nature, the normal occurrence of both Os and Ir is as nuggets made of Os-Ir alloy, usually also containing ruthenium and very small quantities of rhodium.
sbierwagen 5y ago
Theodore Gray has a story about visiting a company with an electron beam furnace with Oliver Sacks to turn a pile of loose iridium beads into a bar: https://theodoregray.com/PeriodicTable/Stories/077.x3/index.html https://theodoregray.com/PeriodicTable/Stories/077.x3/index.... Some of the cost isn't just from using the equipment, but because you'll have some evaporation from melting in vacuum. He says at the start of the article that Sacks started with a kilogram of beads: >After melting from both sides and a lengthy cool down period (plus a couple of "ouch, where are my gloves" moments) Sacks' iridium was consolidated into a block a little over 2" square and less than 1/2" thick, weighing 1.7 pounds. It's startlingly heavy, distinctly more so than a similar sized tungsten block (which would be about 15% lighter and about 10,000% cheaper). If true, the melt lost 22.7% of the mass, which is pretty painful. Google is saying iridium is about $167,000 per kilo right now! I assume they've got a cold trap on the vacuum line, and recovered some of the difference in weight as fine iridium dust, but the rest is going to end up coating the inside of the vacuum chamber. If they routinely melt platinum-group metals, I wonder how often they scrap the entire chamber to melt it down and recover the evaporate.
- adrian_b 5y ago
  Normally all furnaces or vacuum chambers where precious metals may evaporate have their walls covered with some metallic foil, e.g. aluminum foil (while the worked metal is heated at very high temperatures by the electron beam, the walls remain much colder), on which the precious metals lost during heating will condense. After a production batch, the metallic foil is replaced and the used foil is chemically processed and almost 100% of the precious metals are recovered.
  - sbierwagen 5y ago
    Ah, that makes a lot more sense.
- DavidAdams 5y ago
  That story reinforces everything that I've learned about Oliver Sacks. What a cool dude.

tyingq 5y ago

Osmium would be heavier still (22.59 grams/cc), and a relative bargain at $1275 for the 10mm cube at the same source. Not polished/shiny though.

TeMPOraL 5y ago
And, as divbzero's Quora link points out, it's going to kill you by oxidizing into a toxin when exposed to open air.
- tyingq 5y ago
  That seems to be a concern with osmium powder, ground osmium, etc. I don't think that a cube has any handling requirements more exotic than lead solder.
  - GravitasFailure 5y ago
    Less than that even. It's a noble metal and doesn't like to react under normal conditions, though hitting it with a blowtorch might ruin your day.
adrian_b 5y ago
Osmium is the densest pure metal, but iridium has an almost identical density, i.e. 22.56 for Ir, vs. 22.59 for Os. The difference is far too small to give you a different feeling when holding a piece of either osmium or iridium. While osmium and iridium are the densest pure metals, there is a range of composition in the osmium-iridium alloys which has a slightly greater density than both pure osmium and pure iridium. That happens because the atomic concentration of Os is a little higher than that of Ir while the atomic mass of Ir is a little higher than that of Os. While increasing the proportion of Ir in an Os-Ir alloy from 0% to 100%, there is a range where the atomic concentration decreases slower than the average atomic mass increases, so the density of the alloy becomes greater than the density of pure osmium. At higher Ir percentages, the increase in atomic volume overcomes the increase in atomic mass, so the density becomes a little lower than for pure Os. Unlike pure osmium, an Os-Ir alloy would not be dangerous to handle. Pure osmium is slowly oxidized in air releasing the volatile and extremely dangerous osmium tetraoxide. In nature, the normal occurrence of both Os and Ir is as nuggets made of Os-Ir alloy, usually also containing ruthenium and very small quantities of rhodium.

sbierwagen 5y ago

Theodore Gray has a story about visiting a company with an electron beam furnace with Oliver Sacks to turn a pile of loose iridium beads into a bar: https://theodoregray.com/PeriodicTable/Stories/077.x3/index.html https://theodoregray.com/PeriodicTable/Stories/077.x3/index.... Some of the cost isn't just from using the equipment, but because you'll have some evaporation from melting in vacuum. He says at the start of the article that Sacks started with a kilogram of beads: >After melting from both sides and a lengthy cool down period (plus a couple of "ouch, where are my gloves" moments) Sacks' iridium was consolidated into a block a little over 2" square and less than 1/2" thick, weighing 1.7 pounds. It's startlingly heavy, distinctly more so than a similar sized tungsten block (which would be about 15% lighter and about 10,000% cheaper). If true, the melt lost 22.7% of the mass, which is pretty painful. Google is saying iridium is about $167,000 per kilo right now! I assume they've got a cold trap on the vacuum line, and recovered some of the difference in weight as fine iridium dust, but the rest is going to end up coating the inside of the vacuum chamber. If they routinely melt platinum-group metals, I wonder how often they scrap the entire chamber to melt it down and recover the evaporate.

adrian_b 5y ago
Normally all furnaces or vacuum chambers where precious metals may evaporate have their walls covered with some metallic foil, e.g. aluminum foil (while the worked metal is heated at very high temperatures by the electron beam, the walls remain much colder), on which the precious metals lost during heating will condense. After a production batch, the metallic foil is replaced and the used foil is chemically processed and almost 100% of the precious metals are recovered.
- sbierwagen 5y ago
  Ah, that makes a lot more sense.
DavidAdams 5y ago
That story reinforces everything that I've learned about Oliver Sacks. What a cool dude.