O nowej grupie kolekcjonerskiej agatów z Płóczek Górnych (Dolny Śląsk)

Abstract

On a new group of collector’s agate from Płóczki Górne (Lower Silesia, Poland).A b s t r a c t. In Lower Silesia, south-western Poland near Lwówek Śląski, in the vicinity of Płóczki Górne, there are agate deposits in Permian trachyandesite (melaphyre). They are intensely multicoloured, transparent and show numerous morphological structures. A new collector’s group has been distinguished among them: small quartz agates with “quartz suns” (cold quartz suns). These agates account for 5 to 10% of the population of agate from Płóczki. Cold suns grow from small marginal spherulites. They have structures of radial colourless quartz crystals, and show the phenomenon of irisation or rainbowing. Their sharp pyramidal ends, covered with milky chalcedony, form the so-called “dog teeth” or crystal vaults. This proposal of a new collector’s agate group is a useful instrument for the ordering of a large collection.