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Chris Wood




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PostPosted: Oct 13, 2018 23:43    Post subject: Question about Lapis  

Hi. New to the group. I hope I've put this in the right section. I picked up 2 small pieces of Lapis Lazuli at a gem and mineral show today and was wondering what I can use to polish them up. I don't need them to be gemstone quality. I dont have a tumbler. Any suggestions? Thanks in advance.


20181014_003726.jpg
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Lapis Lazuli
Afghanistan
3x6 cm
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20181014_003726.jpg


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alanbartlett




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PostPosted: Oct 14, 2018 13:20    Post subject: Re: Question about Lapis  

It depends on whether you want to create a cabachon or simply want to polish the - from the photo - flat faces. Without some sort of mechanised grinder/polisher a cabachon would be difficult, but sorting the flat faces is perfectly possible - if a little time consuming!

Get some sheets of wet/dry silicon carbide paper and, ideally, a sheet of glass - the glass to give you a smooth backing. Grades 80, 100, 240, 500, 800 and 1200 are probably the best, then simply add some water to the sheet and move the stone in a figure of eight movement until properly flat - wash the stone and continue through grades in the same way. Finally get some cerium oxide powder and sprinkle lightly onto to a felt buff or a piece of leather - spray with water and vigorously rub the stone on it - you should get a reasonable polish which will depend on how fastidious you were in removing all scratches at each step!

Alternatively, find your nearest rock hounding club - fairly common in the US from what I read but as rare as the proverbial here - and see if you can use their equipment.

Good luck with it!
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Chris Wood




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PostPosted: Oct 14, 2018 22:18    Post subject: Re: Question about Lapis  

Thanks alanbartlett. I am trying to shine up the flat sides. I like using interesting rocks and minerals as baking material for my Warhammer 40k figures. Just one question, what is cesium oxide powder?
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Chris Wood




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PostPosted: Oct 14, 2018 22:48    Post subject: Re: Question about Lapis  

Also, when I flip the one on the right over, there are small gold colored bits less than a mm each. What kind of minerals form with lapis? Is this pyrite or something else?


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Tobi




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PostPosted: Oct 15, 2018 08:22    Post subject: Re: Question about Lapis  

Chris Wood wrote:
What kind of minerals form with lapis? Is this pyrite or something else?
Yes, that's pyrite :-)
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alanbartlett




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PostPosted: Oct 15, 2018 08:42    Post subject: Re: Question about Lapis  

Cerium oxide is an oxide of the rare earth metal cerium - widely used by lapidaries for a final polish on stones - and a variety of similar uses throughout industry.
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Dale Hallmark




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PostPosted: Oct 15, 2018 11:06    Post subject: Re: Question about Lapis  

The white could be calcite..that is pretty common with lapis.

The main source is Afghanistan and has been for about 6000 years.

It can also be found in the Chile, Siberia, Angola, Argentina, Burma, Pakistan, Canada, Italy, India, and in the United States in California and Colorado.

Dale
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Chris Wood




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PostPosted: Oct 15, 2018 11:52    Post subject: Re: Question about Lapis  

Thanks Dale. The person I got it from said it was from Afghanistan.
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Dale Hallmark




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PostPosted: Oct 15, 2018 12:59    Post subject: Re: Question about Lapis  

I have a small sample from Afghanistan. I'm quite happy with mine although it isn't anything special. Mine has pyrite in it too.

Dale
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