Feldspar
is a group of minerals that
are very important in rock formation,
accounting for over half the
earth's crust! There are a number
of varieties that are used in
jewelry. The most important
are moonstone,
and labradorite, both known
for their phenomenal iridescence
and adularescence. The following
is a table to help clarify the
feldspars with gemological importance:
| Name |
Chemistry |
Description |
| Pladgioclase |
Sodium
Calcium Aluminum Silicate |
Labradorite
(play of color); Spectrolite
(play of color) |
| Microcline |
Potassium
Aluminum Silicate |
Amazonite
(Bright pastel greenish
blue) |
| Oligoclase |
Sodium
Aluminum Silicate |
Sunstone
(gold spangles from included
platelets of hematite) |
| Orthoclase |
Potassium
Aluminum Silicate |
Moonstone
(transparent with floating
blue) |
Amazonite
was used by the ancient Egyptians for the carving of deities.
The stone was considered a catalyst between the living
and the gods. Moonstone was thought to drive away sleeplessness.
