Iridium APEX Mineral

Iridium (Ir #77) is the next element on the periodic table for my APEX mineral collection.  

Wikipedia Iridium
Iridium Minerals - There are only a few Iridium minerals and these are very rare and small in size.  The only practical Iridium APEX mineral is one that contains native Platinum with trace Iridium contaminants.

Iridium is one of the rarest elements in the Earths crust and is the most corrosion-resistant metal.  It is usually found as an alloy in platinum ores.  Only 10 tons of Iridium are produced each year.

Iridium is one of the six Platinum Group Metals.  These are precious metals which have similar physical and chemical properties, and tend to occur together in the same mineral deposits.

Meteorites contain high amounts of Iridium.  The high amounts of Iridium in the clay layer at the Cretaceous–Paleogene boundary leads to the hypothesis that the impact of a massive extraterrestrial object caused the extinction of dinosaurs and many other species 65 million years ago.   

Iridium was unknown until modern times.

Iridium is primarily used to produce crucibles for growing large high-quality single crystals.  The Iridium is unreactive with most chemicals.

Iridium has no known biological role.