Qapf Diagram Extrusive. There are 2 qapf diagrams one for coarse grained plutonic or intrusive igneous rocks one for fine grained volcanic or extrusive igneous rocks. The acronym qapf stands for quartz alkali feldspar plagioclase feldspathoid foid.
Qapf diagram with rhyolite field highlighted tas diagram with rhyolite field highlighted rhyolite is an extrusive igneous rock formed from magma rich in silica that is extruded from a vent to cool quickly on the surface rather than slowly in the subsurface. The acronym qapf stands for quartz alkali feldspar plagioclase feldspathoid foid. Q a p and f percentages are normalized recalculated so that their sum is 100.
Today the diagram is useful mainly to keep the various rock names straight and to follow some of the older literature.
Q a p and f percentages are normalized recalculated so that their sum is 100. Voor een nauwkeuriger classificatie gebaseerd op chemische samenstelling zie file classification extrusive rocks nl svg. Hundreds of mineral grains are identified and carefully counted before using this diagram. Qapf diagram with rhyolite field highlighted tas diagram with rhyolite field highlighted rhyolite is an extrusive igneous rock formed from magma rich in silica that is extruded from a vent to cool quickly on the surface rather than slowly in the subsurface.
