New Barite Occurrence at Rosh Pinah Mine – Namibia

March 25, 2017

Author: Gisela Hinder, Rosh Pinah Geo Center, Rosh Pinah, Namibia

e-mail: gisela.hinder007@gmail.com

 Rosh Pinah Mine is situated in the southwest of Namibia about 80 km east of Oranjemund. Rosh Pinah Mine became well known for its beautiful barites when a massive pocket of yellow to orange barite crystals was opened in 1989. It is said that these barites were the best ever found in Namibia.

In February 2017 new barite crystals were discovered at Rosh Pinah. Yellowish, unfortunately smallish, barite crystals were found in Southern Ore Field No.1 on 110 level.

 

Yellowish barite crystals on a galena and chalcopyrite matrix, Size 15 x 14 x 12 cm

The barite occurs in a shiny matrix of mainly galena and chalcopyrite in an otherwise leached host rock. Due to the metallic matrix and the lustrous barite crystals, the rock displays an absolute ‘sparkle’ which unfortunately does not display well in the images.

 

 Size 10 x 6.5 x 5 cm

 


Size 11 x 7 x 5.5 cm

Hopefully some bigger barite crystals will be found soon in that area.

 In places the barite is associated with pure white to transparent baritocalcite, or only the latter as shear zone fillings without barite.

 

Almost transparent baritocalcite , 10 x 10 x 6,5 cm


White baritocalcite, Size 7 x 6 x 5 cm

  

Baritocalcite, 5 x 4 x 4 cm

 

GARNET

March 25, 2017

Duncan Miller

Garnets are among the easiest gem materials to facet. They have no distinct cleavage, although some crystals have a parting that causes them to fracture into thin slabs. The rough often is in globular shapes, which is good for weight recovery. When choosing rough, avoid being fooled by fake material. Red glass is sometimes covered in adhering deceptive ‘grit’ to mimic natural nodules. Illuminated from behind or the side with a torch, the characteristic internal swirls and r...


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A Bit about Blue Lace Chalcedony

March 25, 2017

Jo Wicht

Blue Lace “Agate” is found on the farm Ysterputs 254 (meaning iron holes) in Namibia. The mine is located adjacent to the “Blinkpan” (shining shallow lake) which can be seen to the west of the B1 highway about 80 km north of Vioolsdrift and Noordoewer, which are the border towns on either side of the Orange River between South African and Namibia.

Blue lace is not a true agate, but a chalcedony (microcrystalline quartz) laid down in a series of wavy bands, which gives it th...


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The Beryl Family

February 24, 2017

Duncan Miller

Many faceters recommend that beginners start with aquamarine. It usually presents no problems in faceting or polishing, is relatively easy to obtain, and in lighter colour it is not overwhelmingly expensive. Aquamarine is the blue or blue-green gem variety of the mineral beryl, an aluminium beryllium silicate. It occurs in elongated hexagonal barrel-shaped crystals. It is dichroic, with the most intense colour when viewed along the length, the so-called c-axis. This is a pity, ...


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Faceting and Polishing Quartz

January 15, 2017

Duncan Miller

This is the first of an intended series of articles on faceting and polishing a variety of gemstones. I am beginning with quartz because that is what most people start faceting when they first take up the hobby. Quartz rough is inexpensive and readily available in a wide range of colours. It is not necessarily the easiest material to polish, but if a particular stone behaves badly it is no great loss to set it aside to be tackled at a later date. You should try to select rough ...


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Playing With Stars

November 23, 2016

I cut off the end of a damaged Goboboseb quartz crystal because it had a deep purple central inclusion at the one end, which I thought would make an interesting stone to facet.

 But then I noticed that the end of the remaining piece had regular purple stripes radiating from the centre to the points of the hexagonal crystal. So I cut off another section of the crystal to the depth I hoped I would need for cutting a gem.

I first tried to find the middle of the purple star shape, and marked s...


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Who Knows Nigel?

October 23, 2016

Not many people in our club know Nigel Brown, but behind the scenes he must be one of our most productive lapidaries, in and among all his other commitments. His website has been listed in this newsletter’s advertisements for several months now (nigelbrownjadecarver.com). When I looked at it again recently I saw he had been busy producing jade kiwis so I asked him for an update of his work. He sent us this: 

Little Spotted Kiwi

This little...


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THE C-AXIS, WHAT IT IS AND WHY IT IS USEFUL TO GEM CUTTERS

September 23, 2016
by Duncan Miller

All crystals fall into one of seven crystal systems, based on their symmetry. In crystal drawings, by convention, the c-axis usually is orientated vertically, in the plane of the paper. All crystals except those in the cubic (or isometric) crystal system have a c-axis. Cubic system crystals, like diamond, garnet and spinel, have no c-axis because all three crystallographic axes are necessarily the same length. In the other crystal systems the c-axis can be longer or shorter th...


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THE SECRET OF A GOOD POLISH – IS A GOOD PRE-POLISH

August 28, 2016

In the bad old days, one cut facets on a 600 mesh lap, followed by a 1200 mesh lap and then went on to polish. The 1200 mesh leaves quite deep scratches, and on some material produces ‘orange peel’, a mottled surface with alternating rough and smooth patches. This makes polishing tedious. A pre-polishing step, with 3000 mesh or 8000 mesh diamond gets rid of the scratches and any orange peel. You might think the additional step adds time to the process, but in practice it speeds it up beca...


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Selecting Rough

June 25, 2016

By Duncan Miller

If you are going to facet, you need to learn something about mineralogy because you need to know what stones you should obtain, how their characteristics affect their behaviour while you are cutting and polishing them, and how they affect the optical properties of your finished gemstone. The easiest material for beginners to cut and polish is common red garnet. It presents no problem with cleavage or orientation for colour, and generally behaves itself well during ‘cutting...


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