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 Birthstones For August  
 
  
     
    Peridot and Sardonyx have both been considered as birthstones for August.
    The first, Peridot, also known as chrysolite, is a transparent yellow-green
    or leaf-green (or even bottle-green) stone found in New Mexico, Arizona,
    and in the Navajo country in Utah. It is a variety of Olivene, a series of
    minerals with a glassy luster, a hardness of 6.5 to 7, a conchoidal
    fracture, and a fair cleavage. It is found in igneous rock.
  
     
    The other, Sardonyx, a form of onyx, is the more traditional August
    birthstone. It is a variety of cryptocrystalline quartz which has alternate
    banding of white and reddish brown layers. This gem varies from translucent
    to opaque, and makes beautiful cabochons. Brazil, India, and Uruguay are
    the best known sources.
  
 -- by Axel E. Janson  
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