What is Bytownite?
Bytownite is a plagioclase feldspar composition between anorthite and labradorite. It is more important in rock classification than as a common isolated crystal, but well-formed material can be collectable.
Mineralogy and structure
Bytownite has a variable plagioclase formula commonly represented as (Ca,Na)(Al,Si)4O8. It crystallises in the triclinic system and has hardness about 6-6.5.
Colour and appearance
The mineral is commonly white, grey, colourless or pale yellow, with vitreous lustre. Tabular crystals, granular masses and cleavage fragments occur; a weak play of colour may appear in some material.
Formation and localities
Bytownite forms in calcium-rich mafic rocks such as gabbro and anorthosite, as well as in some metamorphic rocks. Localities include Canada, the United States, Norway, Russia, Madagascar and Japan.
Collecting and care
Bytownite is best documented by its host rock and composition because it can resemble other pale feldspars. The guide links it with Labradorite and Anorthite as related plagioclase compositions.
Bytownite and zodiac signs
Popular crystal lists may associate Bytownite with Taurus or Virgo because of its pale colour and stable feldspar structure. These are non-scientific associations.
Symbolic and esoteric associations
Esoteric writing may use bytownite as a symbol of balance between calcium and sodium or between related feldspar compositions. This is metaphorical only.
