Characteristics of Bytownite:

Chemical Name: Sodium, calcium aluminosilicate

Formula: NaSi3O8 – CaAI2Si3O8

Colors: White, grey, yellow, brown

Structure: Triclinic

Hardness: 6.0-6.5

Specific Gravity: 2.7

Refractive Index: 1.56-1.57

Lustre: Vitreous to pearly

Streak: White

Locations: Mexico, Scotland, Greenland, USA, Canada

What is Bytownite? 

Bytownite is the rarest member of the plagioclase feldspar group; the other members of the group that have gem varieties include labradorite, albite, and oligoclase. Bytownite is seldom found in well-developed crystals, but these can be gemmy when found. Its gemstones are usually faceted, with the transparent gems varying in color from a pale, straw yellow to a light brown. A variety from Mexico is marketed under the name Golden Sunstone, but is different from the various other feldspar sunstone.