K-Feldspar and Plagioclase FeldsparFeldspars have two cleavage planes that intersect at 90°. . The feldspars are divided into two main groups: Potassium feldspar ("K-spar") and plagioclase.feldspar quartz potasium,Minerals close-up - USGS Geology and GeophysicsDec 15, 2016 . This image shows some of the most common minerals you'll find in rocks. This pile contains plagioclase feldspar, potassium feldspar, quartz,.
feldspar quartz potasium