SPOTLIGHT: ALBERTO SCARANI, GG, FEATURED PRESENTATION: SYNTHETIC DIAMONDS DEMYSTIFIED: AGA LAS VEGAS, JUNE 1
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 Post subject: Trace elements in cuprian tourmaline from Mavuco Mozam.
PostPosted: Tue Jan 03, 2017 9:10 pm 
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Location: Mars PA
I once stood before a pile of coal at a large power plant with a paint pail in my hands and a request from the office to get a sample to analyze, so we would independently know what quality of coal the plant was burning. It was an impossible task without the implicit assumption, that the pile contents were very uniform in the properties of interest. The plant had standards for their coal buying, but it came from a number of mines and getting a REPRESENTATIVE sample by me was ridiculous.

It is the degree of variability of the source that makes taking a valid sample easy or very difficult. It is my opinion that tourmaline deposits like Mavuco are so variable that getting a representative sample is impossible. I base this opinion on trying to get some of my cuprian tourmaline analyzed, because they did not conform to published data. Most of them were purchased before Mavuco was even identified as a source of tourmaline, let alone cuprian tourmaline. Who was collecting samples of tourmaline then to be sure that the changing nature of the material from the deposit was identified?

I guess the final point I would make, is, how available is the data that is gather from analyzing a tiny percent of all the tourmaline mined at Mavuco? I could not get ANY data from the last lab I sent my cuprian tourmaline gemstones to. Even though I was told that one of them was "The real learning gem in the lot." Two years of waiting for the return of my gems, little holes in their girdles and nothing published. I am not impressed with the gathering of data to define location of origin, with probably the most complex and variable substance used as a gemstone, tourmaline. (And it comes from lots of places.)

Bruce


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 Post subject: Re: Trace elements in cuprian tourmaline from Mavuco Mozam.
PostPosted: Wed Jan 04, 2017 3:12 am 
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Absolutely. If I had unlimited dollars I would definitely sample as many as I could and publish the data freely online. Unfortunately it's kind of hard to find big funding for this sort of work and those most likely to shell out also tend to have a vested interest in keeping the information proprietary.


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 Post subject: Re: Trace elements in cuprian tourmaline from Mavuco Mozam.
PostPosted: Wed Jan 04, 2017 8:47 pm 
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More than the lack of all the money in the world and wanting to retain contol of the data, there is a science to sampling deposits to really know what you have. When you come up with a composite number from very limited amounts of causually collected material, it is not very good science to call it representative of the deposit.

Bruce


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