albiteanortit

Albiteanorthite is a hypothetical end-member of the plagioclase feldspar solid solution series. Plagioclase feldspars are a group of tectosilicate minerals that form a continuous solid solution between albite (NaAlSi3O8) and anorthite (CaAl2Si2O8). Albiteanorthite represents a theoretical composition that would be halfway between pure albite and pure anorthite, containing an equal molar proportion of sodium and calcium cations. In reality, plagioclase feldspars are typically described by their anorthite content, with compositions like An10 (10% anorthite) or An70 (70% anorthite). The term albiteanorthite is not commonly used in mineralogical literature because natural plagioclase feldspars rarely, if ever, achieve this precise stoichiometric composition. Instead, mineralogists use the percentage of anorthite (An) to classify plagioclase compositions, ranging from pure albite (An0) to pure anorthite (An100). The physical and chemical properties of plagioclase feldspars change gradually and continuously across the solid solution series, from those rich in albite to those rich in anorthite.