The Cowell Jade Province, South Australia

​Do you know that the largest current reserves of top quality nephrite in the world are to be found in Australia?  At Cowell in South Australia.  Reserves of around 80,000 tonnes were estimated by the SA Department of Mines & Energy, now the SA Department for Energy & Mining (DEM) some years ago and have probably increased since!
 
But currently, there is no market for Cowell nephrite in Australia and most people don’t even know jade is found here, though it is well appreciated overseas, especially the high quality Black Jade, which is startlingly beautiful.
 
Yet there is a local market for other Australian minerals like opal and coloured Argyle diamonds, and my dream is to have jade pieces selling in every jewellers and tourist shop in the next decade where you can currently find either of the foregoing gems.  Why not?
 
I was told (Jeff Olliver, pers comm) that DEM used to provide a display of Cowell jade along with expert staff to answer questions at the Adelaide Festival of Arts.  This ceased in recent times, no doubt when the previous owner of the exploration lease had problems and production stopped.
 
To resurrect a local industry in SA I suggest the following:

• DEM builds a new display and wheels it out for important events
• the SA Museum develops a display on Cowell jade - I only saw two small pieces of Cowell and one piece of Chinese nephrite in its mineral displays when visiting recently
• TAFE (Technical and Further Education) SA considers re-establishing their jade carving course, which Jeff mentioned was run in the past

 
An upsurge in interest in Cowell jade at home would likely encourage exploration investment, tourism, an awakening to the beauty of Australia’s mineral wealth, new jobs and skills in SA and an increase in the tax take by the state.  So let’s make it happen together!
 
But now back to my story.  My stock of Cowell (bought in NZ many years ago) was running low, to the point where I didn’t have a suitable piece for a carving I wanted to produce for an exhibition in Sydney.  So having previously met in Melbourne with a manager of the company which currently owns the mining lease (Cowell Jade Mining, a division of Gemstones Australia), the need for my wife to travel to South Australia for work was a great opportunity to visit, by arrangement, the company’s operations in Cowell.

​Picture 1 - a pile of large chunks of nephrite pictured in the stockyard.  For scale, even the smaller pieces are the size of a rugby ball.

The company’s stock yard is a dream as you can see above!  But most of the material is boulders weighing up to several tonnes, way too big for me to carry home, let alone cut and work.  Also, with few cut and polished faces on the pieces of rough material it is really hard to tell exactly what I was buying, because I couldn’t tell:
 

• how the fractures run
• the crystal size
• the colour of the stone
• the thickness of the weathering crust
• how does the colour grade through the rock (see Picture 2)?

Picture 2 - a large boulder of jade showing a well developed weathering crust, which is  both a challenge and a joy to incorporate into a carving!

​I was kindly directed to an area of the yard where much of the material had been cut and graded.  Oh heaven!!!  After deciding to purchase about 50 kg of the rocks there, I was kindly invited to visit a couple of the quarries with the manager.  They were everything I hoped for!  The geology of the area is tricky, but fascinating and the new company is working hard at understanding the factors and looking for high quality stone.

Picture 3 - a large lens of nephrite having been stripped of its surrounding metasediments.

There are more than 100 outcrops of nephrite in the Cowell Jade Province.  The host rocks are dolomitic marble and banded calc-silicates of the Palaeo- & Mesoproterozoic Minbie Gneiss, which is around 1.8 billion years old.  The jade formed about 1.7 billion years ago, developing during cooling and folding/faulting of the host rocks (information gleaned from the DEM website).

Picture 4 - a large boulder of nephrite exposed in a quarry, ready for shipping to the stockyard.

​I could bang on about the chemistry and other technical aspects of the province, but if you are interested I’m sure you will check them out for yourself.
 
Only some of the lenses are being exploited because current demand is not that large, and the company has to remove a lot of very hard host rock to expose the elongated pods/lenses of jade, which might be high quality, or not.
 
What can I say?  I learned a lot and I am excited about getting to work on the jade in the near future.  And a big thank you to Gemstones Australia for their kindness and help.
 
I’m going to include further blogs on the Cowell Jade Province in future so watch this space!