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Agate

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The stone was named after the river Achates, where colorful agates were obtained in the ancient times. It is a microcrystalline and cryptocrystalline variety of the quartz group (crystals are visible only through microscopic examination), usually translucent in thin slices, otherwise opaque. The beauty of its stripey appearance can be highlighted by cutting it en cabochon.

 
Agate

Basic properties

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Composition SiO2
Class Oxydes and hydroxydes
Crystal system Trigonal
Mohs' hardness 7
Fracture Conchoidal
Cleavage None
Lustre Glassy
Streak White
Localities Brazil, Uruguay (Artigas), Germany (Rochlitz), India (Gujarat), Madagascar, Mexico, USA (Florida)