Chalcedony 
SiO2 - Silicon Dioxide
Chalcedony is a catch all term that includes many well known varieties of cryptocrystalline quartz gemstones. Chalcedony includes agate, bloodstone, carnelian, chert, chrysoprase, flint, heliotrope, jasper, moss agate, onyx, plasma, prase, sardonyx, thundereggs,, mocha stone, sard, petrified wood, and petrified dinosaur bone just to name a few of the better known varieties.
Colors: It has a waxy luster and appears in a great variety of colors -- usually blue-white, buff, light tan, gray, yellow or brown.
Lustre:
System:
Also, Blue Agate, the Nebraska State Gem, has been found in place in wind-deposited claystones in the Chadron Formation of Oligocene Age in Sioux and Dawes counties. These gems have been found in colors other than blue and the large oval stone is a doublet with a blackened back to highlight the plumes in this material. The chalcedony probably originated from silica that was freed when devitrification (changing from a glassy to a crystalline state) of wind-blown volcanic ash took place. The chalcedony appears to have formed in or near sources of alkaline water.
Technically not a gemstone, but rather the silicified Mississippian Fossil Coral, Lithostrotionella, preserved as the siliceous mineral chalcedony. Designated by House Concurrent Resolution No. 39, March 10, 1990. It is found in the Hillsdale Limestone in portions of Greenbrier and Pocahontas counties and is often cut and polished for jewelry and for display. West Virginia Fossil Coral comes in several colors, including light to dark blue grey, pink, and red.
Care and Treatment
Hardness
Chalcedony has a hardness rating of 7.
Specific Gravity: 2.65 - 2.66
Healing
Touchiness; melancholy; fever; gallstones; leukemia; eye problems; stimulates maternal feelings & creativity. release.
Where Found
Chalcedony is found in all 50 States, in many colors and color combinations, and in sedimentary, igneous, and metamorphic rocks.
Birthstone Months
Star Stone Months
Anniversary Gemstone
Mystical Properties
Lore
Early man made weapons and tools from many varieties of chalcedony including agate, agatized coral, flint, jasper, and petrified wood.
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