MOONSTONES AND FELDSPARS USED IN ESTATE JEWELRY AND VINTAGE JEWELRY
The source of the beauty of feldspars is from their color and iridescence. Their iridescence is caused by scattering of light from thin layers and from a feldspar that develops by internal chemical separation during geologic cooling of an initial single feldspar. Light scattering from layers results in pure, iridescent colors. Feldspars have little brilliance and their crystals are known for their cleavages.
BIRTHDAYS AND ANNIVERSARIES
Moonstone is the alternate birthstone for June.
ORIGIN OF NAME
The name feldspar is derived from the terms "field" and "spar", referring to any shiny rock that cleaves or splits easily. The Anglo-Saxon term "spar" refers to easily cleaved minerals such as calcite, fluorite and feldspar. Amazonite is named after the Amazon River.
Amazonite was often used in Egyptian, Sudanese and Indian jewelry. Amazonite jewelry has been dated back to the third millennium B.C. The 27th chapter of the Egyptian "Book of the Dead' was engraved on feldspar. It as generally accepted that the third stone in Moses' breastplate was amazonite. Around 100 A.D., moonstone appeared in Roman jewelry.
ESTATE JEWELRY HISTORY
Moonstone was a favored adornment during the Victorian Jewelry Period. Moonstone was a popular gemstone in Art Nouveau jewelry. During this period, Cartier and Tiffany created jewelry frequently using moonstone. Sunstone feldspar has been used extensively in Russian jewelry. When large sunstone deposits were found in Norway in the 1850s it became a popular gemstone in Europe.
In India, it was once believed that moonstone was a form of moonlight. It was believed to bring good fortune and help the bearer see future events. In ancient India, young lovers would put moonstone in their mouths under a full moon so that they could see the future. Amazonite was a popular amulet among ancient Egyptians. The Assyrians considered amazonite to be the gem of Belus, their most revered god, it was used in their religious ceremonies. In Europe, eleventh-century lapidary reports wrote that the gem could bring about lovers reconciliation. In the sixteenth century, Cardano wrote that moonstone would drive sleepiness away.
Feldspar is found in substantial portions of many ingenuous and metamorphic rocks. Gem varieties result from the rate geologic conditions that produce clean large grains, mainly in pegmatites and ancient deep crustal rocks.
The major producers of moonstone are Sri Lanka, Burma and India. Amazonite is found in Colorado, Virginia, India, Russia and Africa. Spectrolite, a trade name for labradorite, is found in Finland. Transparent, facet able labradorite is found in Mexico and in Utah, Oregon, California and Nevada. The better quality peristeries are found in Ontario and Quebec in Canada and in Kenya. Norway and Russia are the larges producers of sunstone.
Moonstone is the most valued feldspar. The most valued moonstones are a semi-transparent and flawless variety. Highly valued moonstones also display a bright blue sheen. Labradorite, for a high value, must display an intense iridescent color. Translucent white stones are very inexpensive. Yellow orthoclase is generally considered a collectors stone.
ESTATE JEWELRY CARE INSTRUCTIONS
Ultrasonic cleaners should be avoided, as should steam cleaners, heats, acids and rough handling. Clean, warm soapy water is generally safe to clean the stone.
VARIETIES OF MOONSTONES AND FELDSPARS:
MOONSTONE: Moonstones are found in the gravels of Sri Lanka and Burma and as a byproduct of ruby and sapphire mining. Moonstone comes in blue-white to white iridescence.
LABRADORITE: a dark, opaque feldspar first was found in Labrador. It displays color when it is examined in certain angles. This visual effect is typically bright blue. Colorful iridescence, also transparent stones in yellow, orange, red and green.
YELLOW ORTHOCLASE: a collector's gemstone. It is generally transparent and faceted. Pale to bright yellow from iron substitution for aluminum.
SUNSTONE: Aventurine feldspar is opaque and has glittery golden red inclusions. A second type is transparent, orange, yellow red or colorless and is called labradorite. Labradorite is recognized as the state gem of Oregon. The highest valued is semitransparent and show a lovely reddish or yellow orange glow. Gold spangles from oriented inclusions of hematite.
AMAZONITE: Sometimes called "Pikes Peak Jade" in Colorado. It is a bluish-green variety. Opague, color comes from natural irradiation of microcline containing lead and water impurities. It is also found in Virginia, India, Russia and Africa.
Crystal system: monoclinic (moonstone) triclinic (amazonite, oligoclase and labradorite)
Cleavage: two perfect at right angles and imperfect in a third direction. Parting is common
Refractive Index 1.518 - 1.588
Optic: double refracting and biaxial and AGG reaction is common
Specific Gravity: 2.54 - 2.63 (moonstone and amazonite) 2.62 - 2.65 (oligoclase) 2.69 - 2.72 (labradorite)
With a hardness of 6 to 6.5, on the Mohs' Scale, may crack or cleave if exposed to heat.