Editing Plagioclase (section)

=== In sedimentary rocks ===
Feldspar makes up between 10 and 20 percent of the framework grains in typical [[sandstone]]s. Alkali feldspar is usually more abundant than plagioclase in sandstone because Alkali feldspars are more resistant to chemical weathering and more stable, but sandstone derived from volcanic rock contains more plagioclase.<ref>{{cite book |last1=Boggs |first1=Sam |title=Principles of sedimentology and stratigraphy |date=2006 |publisher=Pearson Prentice Hall |location=Upper Saddle River, N.J. |isbn=0-13-154728-3 |edition=4th |pages=120–121}}</ref> Plagioclase weathers relatively rapidly to [[clay minerals]] such as [[smectite]].<ref>{{cite book |last1=Leeder |first1=M. R. |title=Sedimentology and sedimentary basins: from turbulence to tectonics |date=2011 |publisher=Wiley-Blackwell |location=Chichester, West Sussex, UK |isbn=978-1-4051-7783-2 |edition=2nd |pages=10–11}}</ref>