Anorthite

Ca(Al₂Si₂O₈)

Anorthite is the calcium-rich end member of the plagioclase feldspars. It is uncommon as crystals and can be a major rock-forming mineral.

Selected Australian Occurrences:

• As a constituent of many meteorites.
• As a constituent of the gneiss matrix that hosts ruby at the Mistral Ruby Mine, Mount Riddock, Harts Range, Northern Territory.
• As a fine-grained constituent of sandstone and limestone at the Kara Mine, Tasmania.
• As a major rock-forming mineral in Jurassic dolerites in Tasmania.