Grape chalcedony
Grape chalcedony is one of the varieties of quartz. It consists of spherical aggregates called spherulites that precipitated from SiO2-rich gelatinous solutions. The individual spheres, measuring up to 1 cm in size, are composed of fine filaments of the same length attached to each other. Grape chalcedonies have a soft to intense purple or green colour. The beads are bonded to each other or to the rock backing in a way that resembles grapes. Like any form of quartz, it is very durable mechanically and chemically.
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