The Alvarez Hypothesis proposed that a thin layer of iridium-rich clay represented the impact of a colossal meteorite, which radically changed the climate and ended the era of the dinosaurs. The cause of the dinosaur extinction has long intrigued scientists. Iridium helped answer one of geology’s biggest puzzles – what happened to the dinosaurs? The rapid destruction of the dinosaurs occurred around 65 million years ago and marked the end of the Cretaceous era. Important deposits of iridium are located in the U.S., Brazil, South Africa, Russia, Myanmar and Australia. Like the other PGMs, it is typically mined as a byproduct of nickel and copper production. Iridium is found associated with osmium as the alloy “iridosmium” (or “osmiridium” if osmium dominates). Additionally, osmium plays a role in geochronology–dating rocks. It is also an important oxidant for industrial applications. Today it is used in both electrical and optical microscopy. Previous industrial uses for osmium have included fountain-pen nibs and record player needles. Like iridium, it’s recovered as a by-product from copper-nickel mines. It occurs as an alloy most often with iridium and platinum. The blue-grey metal is highly reflective and is used in space mirrors and other industrial mirror applications. Placer deposits or alluvial (stream) gravels.Intrusive sill structures associated with nickel-copper ores e.g.Ancient (Precambrian) layered intrusives e.g.The four main types of economic PGM mineralization are:
PGMs have a wide variety of uses, but are primarily known for their use in automotive catalytic converts, jewellery, investments and increasingly in advanced electronics. PGMs are all chemically similar to each other and can substitute for each other in some applications. These elements are rare on earth, but abundant in the rest of the universe. Osmium, iridium, palladium, ruthenium and rhodium are typically grouped with platinum and known as platinum-group metals or elements (PGMs or PGEs). What are they, where are they found, and why do they matter? Relative abundance of elements in the Earth’s upper crust. Most of us have heard of gold and platinum, but the other seven are truly rare. These metals are different from Rare Earth Elements, which aren’t actually rare in terms of abundance, but are rarely found in concentrated ore deposits. In terms of abundance in the Earth’s crust, the rarest metals are: gold, platinum, osmium, iridium, palladium, ruthenium, rhodium, tellurium and rhenium.