[Jewelry making - Article 00604] - Re: [Orchid] Yellow Turquoise

[Texeclectic]

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    The Turquoise Group .Turquoise identification and nomenclature is 
    compounded by several problems. Turquoise is part of a group of 3 
    minerals ( Hydrous Aluminum Phosphate and a solid solution of  [
    Copper  - Turquoise ], [ Iron - Variscite ],  [ Zinc - Faustite ] . 

    So Turquoise can be a chemical solid solution containing Copper, 
    Iron, and Zinc in varying amounts .  The  Hydrous Aluminum Phosphate
      allows substitution of some of the ( Copper  and/or  Iron  and/or 
    Zinc  ) . 

    Variscite may be interspersed with other phosphate minerals - ( 
    Crandallite, Wardite, Gordonite, and Hydroxylapite ) 

    If this is not confusing enough, there are several other minerals 
    Prosopite, and Howite are used as substitutes , with and without 
    treatments. 

    Stabilized Turquoise, Treated Turquoise, Reconstituted Turquoise, 
    and Imitation Turquoise, are all separate considerations which add
    to  the confusion. 

    Faustite is yellow - apple  green colored stone. 
    Variscite is yellow - green to blue green. 

    A retired lapidary dealer from Farmington N.M. told me that if it
    would  cut and polish, was moderately durable, and in demand, it was
    likely  sold as turquoise. 

    Gemstones of North America Vol 1 - John Sinkansas. *
    Gem and Lapidary Materials  - June Culp Zitner *
    Color Encyclopedia of Gemstones - Joel E. Arem *
    Gemology II edition - Hurlbut & Kammerling **
    Dana's Mineralogy IV edition - E.S. Dana
    * in print or easily available,    ** in print but expensive,
    Google does not have all these subjects treated well , if at all.

    You expected an easy answer about a gemstone , used from earliest
    times,  available world wide, has such variety and is still so much
    in demand ? It is my favorite gemstone. 

Robb.

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