Chalcedony Gemstones at The Ross Jewelry Company in Atlanta, Georgia.
Chalcedony is a form of quartz that is cryptocrystalline. Microscopically small crystals of
quartz are embedded in opal, which is itself hydrated quartz. The proportion of quartz to opal
varies, and this variation is reflected in differing densities, refractive indexes and other
properties. The quartz crystals are in a fibrous form, sometimes running approximately
parallel to each other, sometimes entwined.
Another name for chalcedony is agate, although the term agate is usually used to describe
banded varieties of chalcedony. Many agates are naturally colored, others are stained for
decorative effect. Varieties include chrysoprase, cornelian (carnelian, sard, sardonyx, onyx,
plasma, bloodstone, myrickite. There are many differently named varieties of agate depending
on their appearance such as moss agate, fossilized wood, and other forms of fossil. Jasper
also belongs to this group, and contains impurities that cause heavy pigmentation.
Technical Characteristics
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Chemical Composition:
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SiO2 - Silicon Dioxide
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Hardness:
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7
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Specific Gravity:
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2.65 - 2.66
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Refractive Index (R.I.):
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1.543-1.552 to 1.545-1.554
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Bi-refringence:
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0.009
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Optic Sign:
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Positive
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Optical Character:
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Uniaxial
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Crystal Structure:
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Trigonal
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The Ross Jewelry Company - 7 Piedmont Center, Suite 104 - Atlanta, Georgia - (404) 495-3720
We are proud members of the following jewelry industry organizations:
Copyright © 1999-2007 - Chalcedony - The Ross Jewelry Company, Incorporated Atlanta, Georgia. All rights reserved.
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