Chalcedony (part1)

Chalcedony is a catch all term that includes many well known varieties of cryptocrystalline quartz gemstones. They are found in all 50 States, in many colors and color combinations, and in sedimentary, igneous, and metamorphic rocks. Chalcedony includes carnelian, sard, plasma, prase, bloodstone, onyx, sardonyx, chrysoprase, thundereggs, agate, flint, chert, jasper, petrified wood, and petrified dinosaur bone just to name a few of the better known varieties.

"Mojave Blue" agate from California.
(Photo is courtesy of Mr. Bill Nicks.)

Because of its abundance, durability, and beauty, chalcedony was, except for sticks, animal skins, bones, plain rocks, and possibly obsidian, the earliest raw material used by humankind. The earliest recorded use of chalcedony was for projectile points, knives, tools, and containers such as cups and bowls. Early man made weapons and tools from many varieties of chalcedony including agate, agatized coral, flint, jasper, and petrified wood.

The move from using certain items as weapons and tools, to using the same items for ceremonial and personal adornment is very easily made. It was only natural for early man to use his finest looking knife for special occasions or to attach a special lance point or arrowhead to his tunic. In fact, agate and petrified wood may have simply been elevated to gems from common and functional weapons or tools.

All 50 States produce some variety of chalcedony, but the material from some States is better known than that from others.

Alaska -- The State has several varieties of chalcedony found at different locations, including agates, jaspers, and petrified wood. Various types of agates can be found in gravel pits and gravels of stream and river beds at several locations in the Chicken Creek area near the border with the Yukon Territory.

Agates, jasper, and petrified wood can be found on many beaches, including those on the islands of Adak, Admiralty, Attu, Kuiu, Kupreanof, Nelson, Popof, Tanaga, Unalaska, and Zarembo. These same materials can be found in the gravels or in many of the streams and rivers of the State. Other well known sources are the outlet of Becharof Lake, Little Nelchina River, and Caribou Creek.

Arizona -- Arizona is well known for its petrified wood because of the Petrified Forest National Park, and petrified wood ranks third in value of commercially produced gemstones. It is generally accepted that the Park contains the most colorful examples of silicified logs in the world.........

Tune in next week for more on Arizona & other states.

Article source: U.S.G. S.