FELDSPAR
Feldspar is a chemically complex group of minerals with a wide range of members.
The two main Feldspar groups that are of interest to gemologists are Alkali Feldspars and Plagioclase Feldspars.
The Alkali varieties include Orthoclase, a monoclinic Potassium Aluminium Silicate with varieties such as Moonstone and Sanidine. Microcline, a triclinic Potassium Aluminium Silicate which includes Amazonite amongst its members.
The second group are the Plagioclase Feldspars, all triclinic Sodium-Calcium series Aluminium Silicates, whose members include Albite, Oligoclase (Sunstone and Aventurine) Andesine, Labradorite and Bytownite.
The chemical and structural differences between these groups, coupled with some specimens having a combination of these properties, gives the gem enthusiast a wide and varied scope of beautiful and fascinating gem materials, from the pinprick schiller of Sunstone to the blue sheen of Moonstone.
The two main Feldspar groups that are of interest to gemologists are Alkali Feldspars and Plagioclase Feldspars.
The Alkali varieties include Orthoclase, a monoclinic Potassium Aluminium Silicate with varieties such as Moonstone and Sanidine. Microcline, a triclinic Potassium Aluminium Silicate which includes Amazonite amongst its members.
The second group are the Plagioclase Feldspars, all triclinic Sodium-Calcium series Aluminium Silicates, whose members include Albite, Oligoclase (Sunstone and Aventurine) Andesine, Labradorite and Bytownite.
The chemical and structural differences between these groups, coupled with some specimens having a combination of these properties, gives the gem enthusiast a wide and varied scope of beautiful and fascinating gem materials, from the pinprick schiller of Sunstone to the blue sheen of Moonstone.