about
a hundred years ago, it was discovered in the Island of St. Paul, near
the coast of Labrador, is the type of one of the four great species
formed by Rose, at the expense of the ancient group of the felspars.
Its specific gravity is 2'6 to 27.
The
labradorite is called sometimes the opaline felspar, because it
resembles the opal in its beautiful reflections of colours. The finest
colours are a play of blue and green upon gray. Yellow and bronze-red
are less common; and a pearly-gray and purple-red still more rare.
The labradorite is essentially formed of silica, alumina, lime, and soda.
It has been found in its crystallized state scattered through volcanic productions, and notably in the lavas of Etna.
LAPIS-LAZULI.
The
lapis-lazuli is a mineral whose beautiful blue colour varies from the
palest tint to a deep blue, nearly black. The finest is a uniform
colour of deep azure inclining to purple. Its specific gravity is 2-6.
Chemists
differ in its analysis; but it is known to contain silica and alumina,
with a supplement of soda, lime, and sulphur. Its colour is of such
enduring quality that the preparation made from it,
