A blue to dark-gray variety of plagioclase feldspar that contains a higher proportion of calcium than sodium and occurs in alkaline igneous rocks.
A bluish to dark gray triclinic mineral of the plagioclase feldspar group that contains a higher proportion of calcium than sodium. Bytownite occurs in alkaline igneous rocks. Chemical formula: (Ca,Na)(Si,Al)4O8.
Origin of bytownite
After Bytown , former name of Ottawa, Ontario, near where a sample of the mineral was found