Kargali, kinda NE of Samarra in Siberia, is a huge copper mining complex
where copper oxides were exploited in antiquity. Literally thousands of
small
shafts. E. Chernykh is the excavator of the complex. I think, if memory
serves me right, he has had a short article in French on it.
Best, Mark Hall
----- Original Message -----
From: Stephen Henley <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, August 28, 2000 12:28 AM
Subject: Re: Copper terms/malachite
> Tony -
>
> Malachite has also been worked in Russia, mainly at various mines
> in the Urals, certainly since the early 18th century (and
> probably long before that), and used among other things for some
> superb decorative inlay work for the Tsars and aristocracy - as
> well as large pieces being used to make giant vases (like the
> British equivalent, the Blue John vases at Chatsworth). Some of
> the mines have an interesting history, being worked by a variety
> of companies at different times. One mine, which I have visited
> recently, was operated by a British-owned company 'Lena
> Goldfields' on lease from the Bolshevik government in the 1920s.
> My Russian hosts told me that there is evidence nearby for the
> deposit having been worked more than 2000 years ago.
>
> - Steve Henley
>
>
> ----- Original Message -----
> From: "Tony Brewis" <[log in to unmask]>
> To: "List" <[log in to unmask]>
> Sent: Saturday, August 26, 2000 7:10 PM
> Subject: Re: Copper terms/malachite
>
>
> > Richard Kelham asks if there was any commercial exploitation of
> > malachite, a copper carbonate/hydroxide.
> >
> > Yes, very much so. Being a nicely coloured stone, it may well
> have
> > been the origin of the Bronze Age, when early people built
> their
> > hearths of the nice green stone and discovered smelting. The
> black
> > oxide, when heated with charcoal, yields metallic copper.
> >
> > One of the earliest "commercial" examples was the use of
> malachite
> > by the Zimbabwe Empire, which produced copper currency from
> > malachite deposits at Kansanshi and Bwana Mkubwa.
> >
> > Typically, malachite forms near the surface in the zone
> penetrated
> > by air and groundwater, so converting the original sulphide
> minerals
> > in an "oxide capping". At Malanjkand in India, for example,
> malachite
> > was the dominant copper mineral near the surface, and at
> Chambishi,
> > Zambia, there was malachite to a depth of 50 metres.
> >
> > The "problem" of malachite for modern technology is that the
> flotation
> > process works best on sulphide minerals, so malachite is lost
> to tailings.
> > Some reagents will collect it, but generally the upper zones of
> ore which
> > contained it were known generally as "refractory" ores. In
> modern times
> > such ores were worked at the Aljoujt mine in Mauritania,
> between 1970
> > and 1983, using a furnace system known as TORCO ( Treatment Of
> > Refractory Copper Ores). Once the open-pit had worked its way
> through
> > the upper zone of ore, which graded 2.7% copper, the furnace
> was
> > closed down.
> >
> > Tony Brewis
> >
>
>
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