Bytownite was first found in 1835 in Bytown (or Ottawa) Canada. It is commonly found as a light cream color. This mineral is a calcium rich member of the Plagioclase solid solution series of Feldspar minerals. It is usually defined as having "%An" between 70 and 90. Like others of the series, bytownite forms grey to white triclinic crystals commonly exhibiting the typical plagioclase twinning and associated fine striations.