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Gyöngyöstarján, Mátra Mts., Heves Co., Hungary
© Tamás Ungvári 2005
| A variety of Quartz A dense, opaque, microcrystalline variety of quartz, usually red, brown or yellow and coloured by oxides of iron. It is used as a decorative stone. The term is also used for other silicified rocks or decorative stones (in particular varieties of rhyolite are often termed Jasper). |