This silvery-white metal contains: 77 protons, 116 neutrons, and 77 electrons. Iridium’s atomic number is 77 with an atomic mass of 192.217. The number of stable isotopes is 2. http://education.jlab.org/itselemental/ele077.html
It is very unlikely to find pure iridium in nature because there is not much found in the earth’s crust. There are a few Iridium Ores in South Africa, Alaska, US, Brazil, Russia, and Australia. In the late 20th Century South Africa was a major producer of Iridium.
Iridium as well as osmium can form an alloy used for tipping pens, and compass bearings. Probably the main use is to harden platinum. Iriduium is also used to make heavy-duty electrical contacts and can also be the stronger material instead of platinum. Such as creating a spark plug. Some of the radioactive isotopes of iridium are used in cancer treatment as radiation therapy. The primary use of iridium is in the manufacture of alloys. “Due to difficulty in extracting iridium, there are not many industrial applications for the element” http://www.chemicool.com/elements/iridium.html http://www.softschools.com/facts/periodic_table/iridium_facts/350/