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Sardonyx or Peridot for August by Harry W. Short, Engineering Geologist The August birthstone, sardonyx is related to sard and onyx, all of which are varieties of chalcedony (microcrystalline quartz). Its bands are colored white and brownish-red, and it is cut into cabochons of red- and white-striped beads 8 to 8.5 millimeters in diameter. The stones have a white base color, with light to dark orange-red stripes showing a different pattern on each bead. Sardonyx is derived from the Greek word sard, meaning reddish-brown, and is commonly used to make cameos. The colored layer is the background, and the white part of the stone is used as relief. Roman soldiers would carve heroes such as Hercules in the stones, believing the stone would make them as brave as the figure in it. In later times, the stone was thought to bring elegance to its wearer and was of value to public speakers. Sardonyx, because of its multicolored bands, was believed by early astrologers to be a gift from Saturn and has also been linked to Mars, perhaps for the same reason.The stone has always been popular, and even though it’s quite common and never had a high value, it has been worn by the rich and the not-so-rich. One story tells that Queen Elizabeth had a beautiful stone set in a gold ring with her portrait carved on the stone. The ring was presented to the Earl of Essex as a token of friendship and to assure him of her help if ever needed. The Earl was imprisoned for treason and beheaded. He tried to send the ring to the Queen for help, but it ended up in the possession of Lady Nottingham, who was an enemy of them both. The Queen learned the truth from the deathbed confession by the Lady of Nottingham. Sardonyx is found in India, Germany, Czechoslovakia, Brazil, and Uruguay. In the United States, sardonyx is found in the Lake Superior region of Minnesota, and in Oregon. August actually has another birthstone named peridot, which is a transparent gem form of olivine composed mostly of magnesium and iron silicates. The color ranges from olive to lime green. The green shade is caused by iron, which shows a brown tinge when the iron content is high. It’s optional as to which gemstone to select, but sardonyx is the usual choice for August. Harry In memory of Harry Short. His articles will continue posthumously. Contact: michele@worldwidedrillingresource.com 32 AUGUST 2016 WorldWide Drilling Resource ®