[Jewelry making - Article 00579] - Re: [Orchid] Lapis grading system?

[Wayne Emery]

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Kevin,

    I'm sorry, but your statement about the absence of pyrite being
    diagnostic of simulated or synthetic laps is mineralogically
    incorrect. Both Chilean and Afghani lapis is often found devoid of
    any sulfide content whatsoever. Some material is almost pure
    lazulite or, rarely, afghanite, but, being a rock (not a mineral),
    there are a half-dozen other minerals that are usually present as
    well. They might include pyrite, hauynite, sodalite, geyerite,
    calcite, mica, and a number of other feldspathic minerals, etc., but
    pyrite need not be present. One of the chemical clues to the
    identification of pyrite is the release of hydrogen sulfide gas when
    hydrochloric acid is applied, but that can be due to the presence of
    pyrite or simply sulfur in the lazurite or longillite, when present. 

    Much of the calcite-rich Chilean material has no calcite whatsoever. 

Wayne Emery
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