Labrador stone or labradorite is sometimes known as opaline felspar,
and was first discovered on the island of St. Paul on the coast of
Labrador.
Labradorite is translucent to opaque, gray-green or brown in color, and
has beautiful chatoyant reflections of brilliant blue, sea-green,
and sometimes red and yellow, changing from one color to another.
Labradorite is 6 in hardness, has a specific gravity of 2.62 to 2.76; a
vitreous to pearly lustre, is brittle, fuses with difficulty before the
blow-pipe, and is decomposed by muriatic acid. It is composed of:
Silica 52.9
Alumina 30.3
Lime 12.3
Soda 4.5
Large masses of this stone are found on the coast of Labrador. It
is also found in Finland, Russia, and the United States. Because of
the dark chatoyant appearance the name of œil de bœuf or ox-eye is
sometimes applied to labradorite. Handsome specimens, cut cabochon,
form pretty ring stones, and many effective engraved cameos have been
produced by using the bright portion for the relief work and the gray
dead part for the base.