The octahedron is a common form but many mixed forms occur as a result of formation and growth conditions. Twinned crystals macles are often seen. Diamonds increase in value with 'whiteness', clarity and size.
However, fancy colours, such as blue, green, yellow, orange, pink and red are extremely rare and therefore very valuable. Australia has been a diamond producer since the nineteenth century. The largest diamond found so far in Australia was mined at the Merlin Mine, Northern Territory, in and weighed It produces a large quantity of stones each year for the international market. This welcome is also a formal component of our Health and Safety induction at Argyle. The Participation Agreement is the formal mechanism through which we ensure that cultural heritage is protected.
For example, every land clearance is conducted in partnership with Traditional Owners, ethnographers, archaeologists and other subject matter experts. In addition, every year, a Traditional Owner annual tour is held on site, during which Traditional Owners have the opportunity to visit and discuss any part of the mine where cultural heritage issues are present, including caves, underground, rehabilitation sites or water sources.
The Argyle mining lease area is on the traditional country of the Miriuwung, Gidja, Malgnin and Wularr peoples. Following several years of relationship building and negotiation, the Argyle Participation Agreement — encompassing post-mining land use, mining benefits, employment and contracting opportunities, land management and indigenous site protection — was registered in as an Indigenous Land Use Agreement.
The Agreement, which superseded Argyle's year-old Good Neighbour Agreement, acknowledges Traditional Owners as the custodians of Country and the Traditional Owners, in turn, recognised our right to mine at Argyle.
A Traditional Owner relationship committee meets regularly to oversee its implementation. We seek to play a positive role in the communities where we operate, as well as in wider society. With the exception of the use of cookies, Rio Tinto generally does not seek to collect personal data through this website.
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A cookie is a small file of letters and numbers that we store on your browser or the hard drive of your computer if you agree. Cookies contain information that is transferred to your computer's hard drive. With the exception of the use of cookies explained below , Rio Tinto generally does not seek to collect personal data through this website. The Regent diamond, found in India, in , became part of the French Crown Jewels until stolen in the French Revolution and eventually set in the hilt of Napoleon's sword.
Alluvial gold miners in Brazil found what they described as 'curious pebbles' in , which were subsequently identified as diamonds. Alluvial diamonds were discovered in in South Africa and in mining of the hard rock sources of diamonds started at Kimberley, the capital of the Northern Cape Province of South Africa. As he walked along the edge of the open pit mine he saw something glinting in the sun so he dug it out using his pocket knife.
What he found was a diamond crystal as big as his fist, more than three times larger than the biggest diamond ever seen! It weighed 3, metric carats or about grams and was perfect - colourless, transparent and flawless. Then in it was entrusted to the famed House of Asscher in Amsterdam for cutting. Asscher spent many anxious weeks planning how to cleave the gem. If his calculations were not correct, the priceless diamond could shatter into a million pieces!
But the gem was cleaved perfectly, into faceted diamonds. Diamond occurs naturally but is extremely rare compared to other minerals. The diamonds may then be picked up by hot molten rock magma and transported upwards as the magma intrudes up into the Earth's crust. These intrusions form narrow cylindrical bodies called 'pipes' and only a very small proportion have significant diamond content.
When pipes are eroded, liberated diamonds may accumulate in alluvial deposits. Diamonds may be found far from their source as their hardness allows them to survive multiple episodes of erosion and deposition. The quality of diamonds can be split broadly into gem, near gem, industrial and boart categories.
Large quantities of industrial-grade synthetic diamonds are made in several countries. It is also possible to make gem-quality diamonds. For hundreds of years India was the world's source of diamonds. However, as that supply started to dwindle, there were smaller finds in Borneo and Brazil.
The discovery of a large diamond deposit in South Africa in the mids helped to meet the world's increasing appetite for these gems. Significant quantities also were mined from alluvial deposits at Copeton and Bingara, near Inverell in north-eastern New South Wales, from to and minor production resumed at Copeton in , but has since stopped.
Numerous minor occurrences of diamond have been recorded elsewhere in Australia. Creek sediment sampling and other exploration techniques in the early to mids led to the discovery of 23 diamondiferous but low-grade pipes at Ellendale in and the Argyle deposit in Three micaceous kimberlite sills. Mulgathing, northwest of Tarcoola. Numerous basic to ultrabasic mica-peridotite plugs and sills with kimberlitic affinities. Drilling at Abminga has recovered crater sediments with kimberlitic affinities at several anomalies, and two small macrodiamonds have been recovered from drillcore at one location.
Townsend, I. Review of diamond resources in South Australia. South Australia. Department of Mines and Energy. The Global Diamond Report About us Initiatives Contact us Petroleum Geothermal. Minerals home Invest Minerals industry value chain Key industry indicators Industry news Mineral commodities. Updated Mining Acts and Regulations Legislation and guidance Best practice regulation Tenement information Exploration data releases Exploration licensing Exploration activities Exploration reporting Forms and lodgement Fees and calculators Public notices Mineral exploration in South Australia Fossicking.
Diamond size is traditionally measured in carats ct , 1 ct being 0. Diamond occurrences in South Australia South Australia is considered highly prospective for diamonds. Three sites in South Australia have each recorded more than diamonds: Diamonds were first found at Echunga near Adelaide by gold panners in , and reports of up to diamonds including 50 saleable gems were recorded through to
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