Ruqayyah Snyder
Jade is a gemstone that has been used for thousands of years to make ornaments, tools, and weapons. Jadeite and nephrite are the two distinct minerals that are referred to as jade. While jadeite is found in rocks that formed under higher pressure than nephrite, Australia only has deposits of nephrite jade. Cowell in South Australia is the only commercial jade mine in the country, with Tamworth in New South Wales being another source of nephrite jade.
| Characteristics | Values |
|---|---|
| Type of Jade found in Australia | Nephrite |
| Number of Nephrite deposits in Australia | 3 |
| Locations of Nephrite deposits in Australia | Cowell, South Australia; Tamworth, New South Wales; and Heemskirk Falls Prospect, Tasmania |
| Year of discovery of deposits | 1965 (Cowell); 1978 (Tamworth); 2015 (Heemskirk Falls Prospect) |
| Commercial jade mines in Australia | Cowell in South Australia is the only commercial jade mine in Australia |
| Age of marble where nephrite is found in Australia | Early to Middle Proterozoic age (2500-1000 million years ago) |
| Colour of Australian Nephrite Jade | Deep green to black |
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What You'll Learn
Cowell, South Australia
The Cowell jade deposits were discovered in 1965 when a local farmer, Harry Schiller, found a 3-4 kg boulder of dense, hard rock near an outcrop of white marble. Adelaide University and the South Australian Museum tested and identified the boulder, and in 1974, 91 jade outcrops were identified by the SA Department of Mines geologists. Today, over 100 outcrops are known, all located within an area known as the Cowell Jade Province.
Cowell Jade exhibits a variety of colours and textures, ranging from grey to dark green, and lensing to dense black. The jade bodies typically have elongated, lensoid shapes in outcrops, and the host rocks are dolomitic marble and banded calc-silicate of the Palaeo to Mesoproterozoic Minbrie Genseiss. The jade deposits at Cowell are estimated to have formed around 1840 million years ago.
The Cowell jade is mined and marketed in three main varieties: green nephrite, black nephrite, and premium black nephrite. The grading and pricing of the jade are determined by its density (specific gravity) and colour. Premium Cowell Black Jade is known for achieving a mirror-like polish using simple lapidary techniques, and all Cowell Jade can be polished to 8000 grit.
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Tamworth, New South Wales
Tamworth in New South Wales is one of only three known deposits of Nephrite jade in Australia. The others are Cowell in South Australia and Heemskirk Falls Prospect in Tasmania.
Nephrite is one of two minerals known as jade, the other being jadeite. However, there are no known occurrences of jadeite in Australia. Nephrite is a magnesium iron calcium silicate, with iron as the colouring agent. A high iron content causes deep green to black colours, while a low iron content results in lighter shades, including the so-called 'mutton fat' jade.
In Tamworth, the jade is found in association with talc in serpentine belts on high ridges at about 3,000 feet. The surface jade seems to have weathered out of the hillsides, and no boulders of jade have been found in the valleys below. These surface pieces are mostly jagged lumps, fractured and heavily weathered and calcined often right to the core. Some of it is a deep green, marbled jade with white wavy lines running through it; it is sometimes fractured along these compacted lines. The surface finds are not of commercial value, but as the digging progresses, jade with fewer fractures is revealed, indicating there is better material still deeper down. Some of the jade is a highly translucent, pale, grey-green progressing to an almost clear jade with spots and blotches of a more vivid, bright green within it.
Between 1977 and 1996, small mining ventures around Tamworth produced about 600 kg of nephrite. Australian nephrite is in demand worldwide and is well up to world standards. It is very tough, the toughest known natural mineral, and is three times tougher than ceramics and even tougher than steel. This makes it an excellent choice for everyday jewellery.
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Heemskirk Falls, Tasmania
Heemskirk Falls Prospect in Tasmania is one of the three Nephrite Jade deposits in Australia, discovered as recently as 2015. Nephrite is one of two gem materials known as jade, the other being jadeite. Nephrite is a magnesium iron calcium silicate, with iron as the colouring agent. A high iron content results in deep green to black colours, while a low iron content results in lighter shades, including the so-called 'mutton fat' jade.
Heemskirk Falls is a waterfall that has mostly disappeared due to dams and irrigation systems, resulting in the flooding of the region, now known as Lake Pieman. However, the upper section of the falls still exists and flows directly into Lake Pieman. The waterfall is incredibly difficult to access by foot, as the known tracks are overgrown, and the bush is very dense. It is possible to see the falls from upstream of the drop, but the river becomes very wide and deep, making further access almost impossible.
Tasmanian Jade is a relatively new discovery, with artisanal mining taking place on Tasmania's western coastline over the last decade. It is incredibly beautiful, rare, and wearable, with attractive, mottled patterns of rich greens, greyish-greens, and occasional splashes of earthy blacks, browns, and greys. It is also totally natural and unenhanced, which is a critical attribute for top qualities of jade.
Tasmanian Jade is expertly cut in Thailand, home to some of the world's best lapidaries. It is cut 'en cabochon', which means it is cut in a convex form and highly polished, but not faceted. This results in attractive smooth domes with a desirable proportion, shape, symmetry, and superior polish that displays an excellent vitreous (glassy) lustre.
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Ogunbil, New South Wales
Nephrite is one of two minerals known as jade, the other being jadeite. Nephrite is a magnesium iron calcium silicate, with iron as the colouring agent. While there are no known occurrences of jadeite in Australia, the country is a major producer of nephrite, which is also known as Australian Black Jade.
Australia has a large mined deposit of nephrite at Cowell, South Australia, and smaller deposits near Tamworth, New South Wales. One such deposit is located in the rural town of Ogunbil, in the Tamworth Regional area of New South Wales.
Ogunbil is home to the Ogunbil Mine, which contains deposits of nephrite jade. This variety of jade is known for its deep green to black colours, which are caused by a high iron content. The mineral is very tough, with a fibrous, interlocking crystal structure that gives it inherent strength and the ability to take on a high polish.
While fine-quality Australian Black Jade is difficult to source and always in high demand, the variety found at Ogunbil is prized for its beauty and rarity. It is sought after globally for its high quality and collectability, making it a desirable material for jewellery and carvings.
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Mulla Creek, New South Wales
Mulla Creek is a river in the state of New South Wales, Australia. The state is known for its deposits of nephrite, one of the two minerals referred to as jade, the other being jadeite. Nephrite deposits can be found near Mulla Creek and other locations in New South Wales, including Tamworth, Ogunbil, Spring Creek, and Nundle. However, Cowell in South Australia is the only commercial jade mine in the country.
Nephrite is a magnesium iron calcium silicate, with iron as the colouring agent. The colour of nephrite jade can range from deep green to black with high iron content, to lighter shades with low iron content, including the variety known as "mutton fat" jade. It is a popular name given to gem-quality tremolite, an amphibole group mineral with elongated, fibrous crystals. This fibrous, interlocking structure gives nephrite its toughness and ability to take on a high polish, making it ideal for carvings and jewellery.
While Australia has a large mined deposit of nephrite at Cowell, the deposit near Tamworth, New South Wales, is smaller. Between 1977 and 1996, small mining ventures around Tamworth produced about 600 kg of nephrite. The process of mining nephrite jade involves extracting large boulders from the ground using excavators in open pits. Jade is then exposed using diamond-tipped core drills, and hydraulic spreaders are used to break it off. Due to its toughness, jade is cut using water-cooled diamond saws and can be further carved and polished for use in jewellery, ornaments, and other decorative items.
The history of jade usage in ornaments, tools, and weapons dates back thousands of years to ancient sites of Neolithic culture in Australia, Europe, Asia, and North and Central America. Jade artefacts have been discovered across various cultures, including Aztec, Maya, Chinese, and Maori. While the term "jade" was used before 1863 to refer to both jadeite and nephrite, Chinese jade artists had previously distinguished between the two, recognising that jadeite was better for fine ornaments and carvings. Today, Australian Black Jade, sourced from nephrite deposits like those near Mulla Creek, is prized for its beauty, rarity, and toughness, making it a desirable material for jewellery and collections worldwide.
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Frequently asked questions
The largest Australian nephrite jade deposit is found at Cowell, in South Australia. Jade deposits are also located near Tamworth, Ogunbil, Spring Creek, Mulla Creek and Nundle in New South Wales.
Fine Australian Black Jade is considered the best quality jade found in Australia. It is incredibly beautiful, rare, and wearable, making it globally coveted.
Mining is done using excavators in open pits. Jade is exposed using diamond-tipped core drills, and then hydraulic spreaders are pushed into the rock so that the jade can be broken off.
Jade has been used for ornaments, tools, and weapons for thousands of years. It is also used for cultural and religious purposes.
