[Jewelry making - Article 00406] - Re: [Orchid] Info on Sujilite?

[Kenneth Ferrell]

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    Sugilite is a material that =was discovered in Africa about 1944 or
    there about it is a pain in the neck to polish due to the natural
    cleavage, although not as bad as Charoite. Here is more scientific
    info on it, also it has now become nearly extinct save for old stock 

	Chemistry: KNa2Li3(Fe, Mn, Al)2Si12O30, Potassium Sodium Lithium Iron
	Manganese Aluminum Silicate. 
	Class: Silicates 
	Subclass: Cyclosilicates 
	Group: Milarite - Osumilite 
	Uses: 	As an ornamental and semi-precious stone used in jewelry and as a
			mineral specimen. 

    Specimens 

    Sugilite is a somewhat obscure mineral named for the Japanese
    geologist who discovered the first specimens in 1944, Ken-ichi Sugi.
    It is becoming very popular in the jewelry trade. It does not form
    well shaped crystals but is usually massive. This is OK, as it is
    used mostly for ornamental and semiprecious stone purposes. It has a
    very distinctive opaque purple color when found in its most desirable
    color shades. The polished stones are mostly opaque with an almost
    waxy luster and a deep reddish purple color. It has been described as
    a purple turquoise although there is no relation between the two
    minerals. Its jewelry uses are becoming widespread and sugilite is
    being used in jewelry styles with turquoise, malachite and coral.
    Some sugilite has been cut into gemstones, but these are very rare.
    The primary structural unit of sugilite is a most unusual double
    ring, with a formula of Si12O30. Normal rings of cyclosilicates are
    composed of six silicate tetrahedrons; Si6O18. The double ring is
    made of two normal rings that are linked together by sharing six
    oxygens, one from each tetrahedron in each six membered ring (notice
    the loss of six oxygens in the double ring formula). The structure is
    analogous to the dual wheels of a tractor trailer and is shared by
    other members of the Milarite - Osumilite Group. 

    Hope this helps, Way back when I think it was around 1980 I bought
    several pounds at a show and was able to pull out nearly 40 CTs Of
    Jelly Sugilite. I have no Idea what that would be worth now, But my
    wife has a very pretty faceted 12 CT. pendant from that rare find,
    Last I had heard Just plain AA (what ever that means) was selling for
    3.50 per gram in rough. 

    Purple Spondilous (spiny) oyster looks as good and is a lot easier
    to cut and polish, Be very careful going for your final polish as the
    surface spaulls quite easy 

 Kenneth Ferrell 
www.shadras.com 


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