Bytownite is a rarer form of
feldspar, more commonly seen as a
faceted gemstone then as a collectors mineral. It is usually translucent without a crystal form. Some other forms of feldspar, especially the transparent yellow form of
Orthoclase, are faceted and incorrectly labeled as Bytownite.
Bytownite belongs to the
Plagioclase Feldspar group, an
isomorphous solid solution series.
Albite is one member,
containing sodium and no calcium. The other end member,
Anorthite,
contains calcium and no sodium. Bytownite is an
intermediary
member of this series. Bytownite is considered by some authorities as a
variety of
Anorthite rather then a separate mineral. The acclaimed
Dana's System of
Mineralogy lists Bytownite as an individual mineral,
whereas the
IMA does not recognize it as individual mineral
species, but rather a sodium-rich variety of Anorthite.
