Vice Chairman of the German Philatelic Collector Group ArGe Zoologie
Croatia will issue a set of two stamps on Rhyolite and Sea Salt on 24th October 2016. Rhyolite is a sour effusive rock of grey to green colour built mostly from the minerals quartz, feldspar, mica and amphibole. It is of porphyric structure with holo crystal granular base.Sea Salt . mineral is extremely important because the sodium ions are indispensable for normal functioning of many physiologic processes in human organism.