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Azurite - Malachite intergrowth from the upper oxydation zone, Tsumeb

Photo : Peter Kolesar

 

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Malachite - Malachit - Malaquita - Malachite

Africa : Namibia : A "Green Hill" of Malachite at Tsumeb

Coordinates : 1914'S , 1742'E : Tsumeb Mine, Otavibergland, Northern Namibia

TSUMEB ... if you are a mineral collector, you know this place for sure. Going there would be the dream of a lifetime for you and indeed the Tsumeb orebody supplied some of the most spectacular mineral specimen of this world ! Not only some of the most rare and diversified minerals occur in Tsumeb, but also some of the true masterpieces of nature, often unrivalled by its beauty from any other source.

It was a great day for me back in 1986, when I was allowed to visit this particular mine and though I missed any major mineral discovery underground such as its famous azurite lined cpecimen chambers, the sheer feeling of "being there" was breathtaking. Last year I was again in Tsumeb, the old grand mine was closed since many years and the shafts are now flooded. However one of the once hardly acessible head gears was now unguarded and so I climbed its steep iron ladders right up to its well preserved winding gear, from where I had a beautiful look around and into the old glory hole, where mining of this exceedingly rich orebody took its beginnings back in 1894.

"I have been holding places of trust for the past 24 years, have visited various countries of the world, inspected mines, mineral outcrops, and prospecting for minerals; have been associated with the minerals gold, silver, tin, copper and lead; but in the whole of my experience, I have never seen such a sight as was presented before my view at Soomep (Tsumeb) and I very much doubt if I shall ever see such another in any other locality..." (Matthew Rogers, 1893).

These famous words, spoken by one of the most experienced mining engineers of its time, gives a vague impression, of how great the "Green Hill" of Tsumeb must have been. A sizeable steep rugged hill, 12 m high, 40 m wide and 180 m long, build out of solid malachite, azurite and a few minor other copper secondaries. What a spectacular sight ! Pity that only very few photos survived to our days and those, that do, are just monochrome.

This "Green Hill" was Otjisume in the language of the local Ovambos : "The place of the green algae", because the green colour of the malachite reminded the locals of the colour of fresh algae. In fact it was a place long known to the coloured people, which belonged to the Khoi-san (Bushman) People. These where the first miners of the green ore, which they traded to the more knowlegdeable Ovambos for early custom smelting.

Otjisume soon became Tsumeb under the first Whites and the Green Hill was mined in a short period and reduced to sacks and wagons of high grade ore. Mining continued into the depth, turning the once prominent hill into a deep open pit and finally into an underground mine, which eventually reached a depth of 1500 m !. Mining continued over 91 years until 1996, hoisting a total of 90 million tons of rich ore with a pure metal content of 4 million tons, half of which was copper.

Today the once flourishing Tsumeb mine is quieter. Active mining has moved out of town to nearby deposits and there is still some limited activity of ore processing going on on the mine grounds. A trial to mine mineral specimen frümm old near surface stopes between 2001 and 2004 had little sucess, though it apparently struck some hitherto unknown massive sulphide ore. So maybe the last word of reopening the "Old Lady" of Tsumeb is not spoken yet...

 

The Tsumeb "Green Hill" in a nutshell :


Mineralogy :

Malachite and Azurite with some lesser important secondary copper minerals

Crystal Size :

Individual crystal size is moderate and may have reach some centimeters

Geology & Origin :

"Surface expression" = Oxydation zone of a major pipe - like sulphide deposit. The hill form originates from a gain of volume during the transition from sulphide to oxyde / carbonate.

Current status :    

Rapid exploitation of the "Green Hill" during the first years of mining operation. Today all what is left is the "negative", i.e. an elongated open pit.

Remarks :

A must see when you are in Tsumeb. Ask any local and he certainly will show you the way.

 

 

 Other notable & famous malachite occurences :

Note : Malachite is a common copper mineral, however much of the malachite forms either botroyidal masses or more or less concentric sprays of fibrous crystals.

- Large botroyidal masses of malachite has been mined from the Ural mountains, Russia and were used as ornamental stones and slabs.

- Similiar large masses of malachite are known from various mines in the Shaba / Katanga province in the southern Kongo.

- Large crystals of malachite are rare. Well known localities with thick crystals up to 5 cm (?)size are the Friedrich mine near Wissen an der Sieg, Germany and Rudabanya, Hungary

- Excellent large blocky crystals up to 4 cm size have been found in 1997 at the old Kalengwa mine in Zambia.

 

 

Historic photo of the rugged malachite outcrop of the "Green Hill"

Photo : Historic, on display in the Tsumeb museum

 

Geological Profile of the Tsumeb orebody, showing the original Greem Hill / open pit area

Photo : Giant Crystal Project, on display in the Tsumeb museum

 

Todays view of the Tsumeb open pit

Photo : Giant Crystal Project

 

 

Resources and relevant weblinks :

For more information on the mineral malachite please look at www.mindat.org, Webmineral and the german Mineralienatlas. See also here for much more information.

Due to its geological and mineralogical interest, there is a vast literature about the Tsumeb deposit, both written and online. So best thing is just to google a bit around and you will probably find more to read than you are asking for. Here is a short list of literature, quoted from Mindat, but there is much more around :

- Strunz, H. (1959): Tsumeb, seine Erze und Sekundärminerale, insbesondere der neu aufgeschlossenen zweiten Oxydations-Zone. Fortschr. Mineral., 37, 87-90.

- Keller, P. (1984). Tsumeb. Lapis, 9 (7/8), 13-64.

- Keller, P. & Innes, J. (1986): Neue Minerale von Tsumeb. Lapis, 11 (9), 28-32.

- Gebhard, G. and Schlüter, J. (1995). Tsumeb, Namibia: Interessante Neufunde und Neubestimmungen. Lapis, 20 (10), 24-32.

 

 

 

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