Chalcedony in Rhyolite (igneous rock)Your model is disabled. For more details go to Edit properties3D Model
Locality: Techereu, Romania
Size: 12.5 x 10 x 1.6 cm
Type: Igneous extrusive (volcanic) rock
Description: Rhyolites are aphanitic rocks, commonly porphyritic, consisting of quartz, Alkali-feldspar, ± plagioclase, and/or volcanic glass of appropriate chemistry. The groundmass or fundamental mass is hyaline or hypocrystalline (as is in this case). Phenocrystals are represented by quartz, alkali feldspars (mainly orthoclase), and rarely plagioclase, mafic minerals. Banded chalcedonies (a sub-variety of quartz, whether parallel or concentric) are called agates. The most common host rocks for agates are extrusive igneous rocks.
Essential minerals: quartz, potassic feldspar (orthoclase, microcline), ± plagioclase, biotite.
Accessory minerals: volcanic glass.
Concept & 3D-modelling by dr. Andrei Ionut APOPEI