What is Feldspar?

02/03/2018 47 0 0


Feldspar is the most common rock forming mineral at the earth's surface.
The different stones in the feldspar species provide jewellery makers with some of the most visually appealing stones. It provides a great choice of natural colours, comes in large sizes and is good value for money. It also has some beautiful optical effects. The feldspars are often described as having "schiller" which is an opalescence or adularescence. These terms all refer to the effect that appears to sit just below or above the surface of the stone when it is placed or moved  under a light.

Above- Moonstone Jewellery at Modern Vintage Style

Optical Effects of Moonstone

Moonstone is well known for this optical effect, in which reflected light, causes blue or white schiller. This internal reflection of light, or  "ïnterference" also produces an iridescence, an example is the rainbow colours seen in labradorite. 

Two Distinct Varieties of Feldspar
The feldspar group is subdivided into two distinct varieties, the orthoclase (alkali) feldspars, which include moonstone, orthoclase , and amazonite, and the plagioclase feldspars, including labradorite and aventurine feldspar.

Sources of Feldspar

Moonstone- the best blue moonstones come from Madagascar, Myanmar (formely Burma), and Sri Lanka. Moonstone is also found in Australia, Brazil, India, Mexico, Tanzania, and United States.
Orthoclase - Yellow and colourless orthoclase occurs in Madagascar, Myanmar, and Sri Lanka.
Amazonite - The main source is India. Also found in Brazil, Canada, Namibia, Russia, Tanzania, United States.
Labradorite - Found in Canada, Madagascar, Mexico, Norway, Russia
Sunstone - Canada, India, Norway, Russia, United States

Pricing Feldspar
Rainbow moonstone is much cheaper than blue moonstone. Good crystal-clear green moonstone is moderately priced. It is more expensive than rainbow monstone