The element iridium is more likely to be found in Solar System asteroids than in the Earth’s crust. Yet a Yorkshire, England, chemist identified the element in 1803. He found it in the residues from the solution of platinum ores. His name was Smithson Tennant.
“In 1801 Tennant worked with a colleague, Wollaston on a 186 kg mass of Columbia platinum ore (‘platina’) (3). In outline, platinum is soluble in aqua regia, a mixture of concentrated nitric and hydrochloric acids. When platina is dissolved in aqua regia, a highly coloured solution and a black residue are obtained, indicating the impurities in the ore. Tennant fused the insoluble residue with alkali at high temperature and dissolved the resulting cooled solid in water, producing a further black solid and a yellow solution. The yellow solution was probably a basic form of osmium tetroxide, OsO4. The black solid was further treated with hydrochloric acid, the solid produced was fused with caustic soda and further treatment with acid obtained red crystals. These are most likely to have been Na2[IrCl6]·nH2O. On heating these, a white powder of an unknown element was obtained, which was later identified as iridium. The Royal Society’s Copley Medal was awarded to Tennant on his 43rd birthday, 30th November 1804, to mark the intricate experimentation that lay behind these isolations.”From https://www.technology.matthey.com/article/55/3/196-200/
Now chemists were able to list iridium in their table of elements with the symbol Ir and atomic number 77. Natural iridium often contains distinct amounts of Os,( osmiridium) Ru (ruthenosmiridium) or Pt.
The definition of iridium now incorporates old “osmiridium” and “ruthenosmiridium” mineral species (all have Ir as the dominant element).
Geologists of the 21st century could refer to iridium when exploring the impact of a massive asteroid, 65 million years ago, in the Yucatan Peninsula, Mexico.
They had located carbon cenospheres deposited when the asteroid hit next to a thin layer of the element iridium. The iridium-laden dust is believed to be the shattered remains of the 200-km-wide asteroid’s impact.
Iridium is one of the rarest elements in Earth’s crust, with annual production and consumption of only three tonnes. It is found in meteorites and thus the mining of iridium is in areas which have historically been impacted by meteorites. It is also commercially obtained as a byproduct of nickel refining.
There was an asteroid event 2.15 million years ago. It has been named the ‘Eltanin asteroid collision’. After the research vessel Eltanin. An Eltanin impactor 4 km in diameter would have blown an initial cavity as deep as the ocean and 60 km wide into the South Pacific and delivered a 200–300 m high tsunami to the Antarctic Peninsula and the southern tip of South America 1200–1500 km away.
“The possible impact site was first discovered in 1981 as an iridium anomaly in sediment cores collected by the research vessel Eltanin, after which the site and impactor are named. Later studies were done by the vessel Polarstern. Sediment at the bottom of the five km (3 mi) deep ocean in the area had an iridium enrichment, a strong sign of extraterrestrial contamination. Possible debris from the asteroid is spread over an area of 500 km2 (190 sq mi). Sediments from the Eocene and Paleocene were jumbled and deposited again chaotically. Also mixed in were melted and fragmented meteorite matter. The area near the Freeden Seamounts over 20,000 km2 (7,700 sq mi) has a meteorite material surface density of 10–60 kg/m2 (2.0–12.3 lb/sq ft). Of this, 87% is melted and 13% only fragmented. This area is the region of the Earth’s surface with the highest known density of meteorite material coverage.
The disturbed sediment had three layers. The lowermost layer SU IV is a chaotic mixture of crumbled sediments in the form of a breccia. Above this is layer SU III consisting of layered sand deposited from turbulently flowing water. Above this is SU II layer with meteorite fragments and graded silt and clay that settled out of still but dirty water. “
Today, the much in demand platinum metals, the six platinum-group elements (PGMs) — platinum, palladium, rhodium, iridium, ruthenium and osmium — are mainly produced in South Africa, but they are across the globe in South America.
Platinum was first discovered in South America in 1735, and the rivers along the west coast of the continent are rich in the metal. In fact, all platinum came from South America until about 1820, when explorers found deposits in Russia and South Africa.
Discovery of the Wilkes Land mass crater, is a type of fingerprint indicating the impact of an asteroid four to five times larger than the one that wiped out the dinosaurs.
The scientists who discovered the anomaly have suggested that this asteroid could be responsible for the worst mass extinction in our planet’s history, and may also have initiated the breakup of the supercontinent, Gondwana. See https://newstarget.com/2017-01-20-massive-strange-anomaly-discovered-under-the-frozen-ice-of-antarctica.html
This was when what we know today as South Africa and South America were once joined in the landmass named Gondwana. That today we have major platinum mining companies active in these now separate continents should therefore come as no surprise.
- Since Ir is resistant to corrosion, it is mixed with osmium to produce alloys used in pen tips and compass bearings.
- Standard meter bars, crucibles and spark plug contacts prepared from a mixture of 10% iridium and 90% platinum have a high melting point and low reactivity
- Iridium-192, a radioactive isotope of the metal, is a potential therapy for prostate cancer Ir implants can be used in the radiotherapy of breast cancer
- Iridium combined with platinum have been made into electrodes that may have the potential to manage hearing impairment.
Smithson Tennant would never have anticipated the applications for his identified iridium. But he was educated to a sufficient level to place him above the ‘masses’ in 1803. He would already be respected by those who would never receive an education, and he was contributing to the technological developments which we hail for their brilliance. We can always see a benefit to the quality of life for those in richer nations, but those benefits do not reach those at the brutal edge of making those benefits possible – those who constitute cheap labour. That can’t be right in the 21st century.
Miners striking in South African Platinum Mines
On 4 December 2007, the Union went on strike to protest working conditions in South Africa’s mines. The strike was spurred on by a rise in worker fatalities from 2006 to 2007, despite a government plan in October to reduce fatalities. Less than 5% of mineworkers came to work on that day.
It is estimated that between the 12th and the 14th of August about nine people (at least four miners, two police officers and two security guards) were killed in the area around Marikana – though there is conflicting reports on who killed whom during these dates.
On 16 August, police opened fire on a group of miners who had gathered on a hill near Nkaneng, at least 34 people were killed at Marikana, 78 were injured and 259 were arrested. The miners were carrying machetes and had refused a request to disarm. According to the Congress of South African Trade Unions, police had first used tear gas, water cannons and then used “live ammunition”. The killings have been labelled a massacre throughout the media with police, Lonmin and NUM itself being blamed.
In 2012, an image of some of the 12,000 miners sacked from the Anglo American Platinum mine near Rustenburg.
In South Africa 2014 – https://www.miningreview.com/news/infographic-platinum-mining-in-south-africa-stats/
The rage of those forced into cheap labour work involves longtime struggles and low pay faced by miners in South Africa whose economy depends on harnessing their energies to mine these precious minerals from the ground. A lot of human energy, for little pay and a tiny amount of ultimately refined platinum as a result.
Cheap labour is exploited globally to ensure expansion of corporate activities. Corporates have ensured they are backed by the laws of the land where they hold assets. These laws are backed by brutal modes of silencing opposition, or quiet coercion. The end game is to satisfy shareholders they will receive regular dividends.
This is where we are in the 21st century. We are stuck in the wheel of ever decreasing returns as diminishing natural resources are ripped from the Earth to try and maintain the guise of momentum. We do not, with all our so called ‘superior intelligence’ to other life forms, seem to be able to step back from this old model of theft of natural resources. We could develop rejuvenating rather than destructive activities. We could enable all human beings to become independent contributors to this process. We seem to be using very little brain power to end the repetitive cycle of harm to the Planet and harm to each other.
Old habits die hard: