Tags: Chemical Substance, Mineral.
Plagioclase is an important series of tectosilicate minerals within the feldspar family. Rather than referring to a particular mineral with a specific chemical composition plagioclase is a solid solution series more properly known as the plagioclase feldspar series (from the Greek oblique fracture in reference to its two cleavage angles). This was first shown by the German mineralogist Johann Friedrich Christian Hessel (1796–1872) in 1826.
