[1][2] The 'A' stands for Anorogenic or Anhydrous, as these granites are characterized by low water content and a lack of orogenic or transitional tectonic fabric.
[4] The addition of the A-type granitoids was proposed by Loiselle and Wones in 1979 however this type was based on tectonic regime and geochemical characteristics.
[5] Chemical characteristics of A-type granites include high silica, alkalis, zirconium, niobium, gallium, yttrium and cerium.
[6] By using Ga/Al ratio, fractionated felsic I or S-type granites can overlap in apparent composition.
[2] The source could be dry granulite left over from the loss of wet magma during orogenies.