The rarest of all plagioclase feldspars (albite-anorthite solid solution series). Bytownite has an anorthite content of 70-90%.
Bytownite Shop
Bytownite from Canada
Origin of name: firstly described in 1835, the mineral was named after an occurrence in Bytown (since 1855: Ottawa), Canada. Bytown owes its name to the English engineer John By, who played a major role in the construction of the Rideau Canal, connecting Ottawa to the city of Kingston at Lake Ontario.
Bytown is still used as a nickname for Ottawa.
Synonyms and trade names: Mexican bytownite has been marketed as "golden sunstone"
Can be confused with: other Feldspars and a plethora of colourless to golden yellow gems.
Localities: as of Spring 2015, mindat.org lists 167 occurrences on all continents.
Probably the most important localities are in Mexico, the USA and in Canada
Bytownites from Ethiopia
Handling: due to the perfect cleavage bytownite should be set, handled and worn with care. Do not clean ultrasonically! Sensitive to acids and brines.