Rogue Trader
freely admits to licking rocks
"Don't cry because you are leaving, smile because you were there."
Member since December 2008
Posts: 839
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Post by Rogue Trader on Mar 11, 2009 12:31:46 GMT -5
Hi, does anyone have any ideas on what this rock is? I have several of them, they are all very round(ish). Maybe a little larger than a baseball. Being colour blind I have to ask my little people what the colours are. They tell me they are black with green bits. I hope you can see them ok in the pictures. These are quite tough rocks, well this one took 5 hits with a 3lb club hammer and a 1" cold chisel before giving. On the outside they are quite flaky. The next picture shows my fingers after rubbing them on the outside of the rocks. As can be seen they flake away rather like fish flakes. Considering that it took so many hits to break it open I was surprised at how clean it broke and how slowly it broke open too. It never actually shattered it was more as if it finally gave and hatched open. The next picture shows the rock open. There were four pieces, but I've already thrown one piece into my rock bucket. There are some very straight clean edges to the rock, almost cuboidal inside. I have marked the picture to show three very clean smooth faces on the bottom piece or rock. The bottom piece doesn't show the clean smooth surfaces quite as well as the two top pieces of rock. Your help in identifying this rock is much appreciated. John.
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bouldergal
freely admits to licking rocks
Glacier Meadow
Member since July 2007
Posts: 783
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Post by bouldergal on Mar 11, 2009 17:12:02 GMT -5
Maybe serpentine? It can be very solid or flake apart easily.
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Sabre52
Cave Dweller
Me and my gal, Rosie
Member since August 2005
Posts: 20,456
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Post by Sabre52 on Mar 11, 2009 22:29:32 GMT -5
John. looks like it has some red in it with green and black and some iron staining. I'd say it's more ruby in fuchsite as the fuchsite is chromium mica and would flake off the outside. The rubies would be the geometric sided crystals. The brown iron staining makes it less desirable for cabbing than the stuff that's the lighter green with the white around the red rubles......Mel
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Rogue Trader
freely admits to licking rocks
"Don't cry because you are leaving, smile because you were there."
Member since December 2008
Posts: 839
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Post by Rogue Trader on Mar 12, 2009 15:01:16 GMT -5
Have today been in touch with the Natural History Museum in London, they have one of the largest mineral collections in the world (417,000 specimens.)
Having looked closely at these photographs they were unable to give a definative name to this rock, so have suggested that I send them a sample of it for their full testing and analysis.
Watch this space for further up dates.
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Post by frane on Mar 19, 2009 18:06:36 GMT -5
I am looking forward to finding out! There is more color inside than the outside showed. Fran
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Rogue Trader
freely admits to licking rocks
"Don't cry because you are leaving, smile because you were there."
Member since December 2008
Posts: 839
|
Post by Rogue Trader on Mar 20, 2009 3:20:57 GMT -5
Received initial report via email today:
I received it today and have had a quick look at it. In simple terms I can tell you that it is almost certainly an altered garnet crystal. The exterior shape, although a bit rough, is very typical of garnets (geometrically it is a rhombic dodecahedron). The exterior is altered to a mixture of dark mica (probably biotite mica from its colour) and a green scaly mineral which I can’t really identify by eye, but which might be a member of the amphibole group of minerals. Although I have not yet undone the sellotape and taken it apart, the alteration appears to have gone quite deep into it, such that there is relatively little of the original garnet left, although I can see some reddish-brown material on the broken surface (maybe there is more inside).
Garnet is a hard material (hence its use in emery paper and abrasives) which will give you a problem unless you have a diamond saw.
While clear well coloured examples do produce decent gemstones (facetted and cabochon), this sample is neither clear nor coloured. The outer alteration rind would almost certainly crumble away in any case, leaving you with a rather murky brown material. In some ways it may have been better as a mineral specimen in its own right.
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