23 Nisan 2013 Salı

Oregon State Gemstone

Oregon State Gemstone

Oregon Sunstone

A sodium calcium aluminum silicate, sunstone is a variety of feldspar with an orange-brown background color and small hematite inclusions. Sunstone has been found in southern Norway and Siberia, as well as in Oregon, North Carolina, Utah, and Pennsylvania in the United States. The variety called Oregon sunstone is a calcium-rich, transparent type of sunstone with copper inclusions instead of hematite. The inclusions give sunstone and Oregon sunstone their characteristic sparkle, known as aventurescence, and make them suitable for use as gemstones.
The premier U.S. gem-quality feldspar known as sunstone is red labradorite. Its only known deposits are in Oregon. Large quantities of gem-quality sunstone, most of it water-clear, straw yellow, or yellow, have been produced from deposits in southeastern Oregon for many years. In sunstone, the labradorite contains millions of copper platelets that reflect the light with varying intensities, resulting in a golden-red play of color known as schiller. Although the common color of Oregon sunstone is straw yellow, varying amounts of copper can cause the stone to be pink, peach, red, salmon red-orange, red-green, and blue-green. It also can be bicolored and tricolored in combinations of yellow, red, and green, and a small percentage displays two or three different colors when viewed from different directions.
In 1988, the availability and quality of sunstone, other than the standard yellow Oregon variety, drastically increased with the discovery of the deposit that was to become the Ponderosa Mine. The vivid red faceted stones and velvety red cabochons from this mine set a new world standard for beauty, not just for red sunstone, but for any sunstone. The opening of the mine also increased the supply of peach, salmon red-orange, red-green, green, blue-green, and bicolored and tricolored sunstones in combinations of yellow, red, and green.
For the first time ever, there was a continuous U.S. supply of the more desirable colors in most of the calibrated sizes (up to several carats) needed by the jewelry industry. The supply from the Ponderosa Mine in Oregon and from other developed deposits will continue to be adequate for many years into the future. In August 1987, the Oregon state legislature designated Oregon sunstone as the official state gemstone.
The shimmering effect of sunstone and Oregon sunstone might remind one of sunlight.
Oregon sunstone occurs in partially decomposed rock in south central and southeastern Oregon. This rock was formed in molten lava and then discharged onto the earth’s surface by volcanic activity. The crystals are found in matrix within the lava flow and are released from the rock through erosion.
Oregon sunstone deposits are located at Ponderosa Sunstones Mine in Harney County, Oregon, and Dust Devil Mine in Plush, Lake County, Oregon, in the United States.
Sunstone has been known for thousands of years. Vikings believed it helped with navigation, and these stones have been discovered in Viking burial mounds. People once believed that sunstone had magical properties. It was used to invoke the energies of the sun. In ancient Greece, sunstone represented the sun god, bringing life and abundance to the gem’s owner. The native people of Oregon exchanged Oregon sunstone in trade and barter. Today, some believe sunstone to provide protection, increase energy levels, and aid contemplation.
Sunstone is relatively rare, brightly colored, and transparent, making it an excellent gemstone. Crystals as large as 3 inches (7.6 cm) across have been found. According to Spectrum Sunstone Mine near Plush, Oregon, a red sunstone weighing 81.25 carats now holds the record for the world’s largest faceted red Oregon sunstone. In 2004, a suite of carved and faceted Oregon sunstones was donated to the Smithsonian Institution’s National Gem Collection.
Oregon sunstone attracts collectors and miners to south central and southeastern Oregon, bringing tourism and commerce to the remote region. Several mines are open to public digging for a fee, and the U.S. Bureau of Land Management has established a free, public collecting area.
State Gemstone
Oregon Sunstone
State Gemstone
Uncut Sunstone
State Gemstone
Cut Sunstones Showing Variety of Color
Group: Feldspar
Chemical Formula: (Ca,Na)((AI,Si)2Si2O8)
Crystal Structure: Triclinic
Hardness (Mohs): 6-7.2
Color: Clear, yellow, shades of red and green
Transparency: Transparent to translucent
Luster: Vitreous
Refractive Index: 1.525-1.58
Density: 2.64-2.66
Streak: White
Cleavage: 001 Perfect, 010 good
Fracture: Conchoidal

Some data courtesy of the Mineralogical Society of America
Author: World Trade Press

Hiç yorum yok:

Yorum Gönder