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19.02 Brazil container received with 11 new rough stones (Cheetah, Bronzite, Hematite, Blue Quartz) 20.02 Tucson shipment with 33 new books, fossil whale ossicles, knightia fish and 66 new stone products. 21.02 Madagascar container received with 3 new types of stone. A total of 90 new products, come to Berghem or order in the webshop. (Note: Friday 28 and Saturday 29 September a.s. closed!)

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Rhyolite from Australia, tumbled

Rhyolite from Australia, tumbled


Rhyolite from Australia, tumbled


Beautiful and especially well-cut stones in top quality.


More information

The solidification ryolite or liparite is an effluent rock with a felsic composition, defined as more than 68% silica. The name ryolite is derived from Greek rhyx "lava flow" Ryolite, due to the extrusion of the rock, has small crystals. In the case of effluents, the magma (and from that moment called lava) cools rapidly to very quickly, leaving no time for the minerals to develop large crystals. Ryolite usually consists of minerals quartz, calivel spoon and plagioclase. Traces of more mafic minerals such as biotite, amphibious and pyroxen can be present in ryolites. Due to the high silica content in ryolite, the molten rock is very viscous (viscous). As a result, lava streams with a ryolite composition will be much less mobile than the low viscous mafic and thus fast-flowing basaltes. If ryolite cools so quickly that it can not form any crystals, it is spoken of a vitrophyric or volcanic glass. The best known variant of this is obsidian. Ryolites come across wherever high viscous magma despite sprays can reach the surface and quickly solidify. The deeper variants of ryolite are the pavement granopher and the deep-rooted granite. Ryolite, also known as koga in Japanese, occurs in hills of the Scottish Glen Coe valley such as Buachaille Etive Mòr, Niijima, Japan and Italian Lipari. Also on the New Zealand North Island and in Iceland there are Ryolite volcanoes. Due to the mineral composition, ryolite is often light in color. This color can also vary from white to pink to light green. Ryolite has a very bright color in the landscape, sometimes even so bright that it appears as if the light emits. Beautiful examples of this can be found at Landmannalaugar, an area in Iceland.