| The Very Highest Quality Jade Information. . . |
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Bi-coloured Amethyst Citrine
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Jade
Jade is a crystalline rock or mineral composed of silicon dioxide.
It is actually very common, and occurs in many varieties, a number of which are gemstones, some of which are very beautiful and very rare.
Different Groups of Jade Gemstones
There are a number of different groups of jade gems, differentiated by their exact composition and crystalline structure. These groups are:-
- Fully Crystalline Jade
This group includes rock crystal, amethyst, citrine, cairngorm and smoky jade.
- Quartzite
Quartzite is composed of an interlocking mass of jade crystals with irregular boundaries, produced by metamorphic processes. It may contain small crystals of mica or other iron bearing mineral. This group includes aventurine jade.
- Cryptocrystalline Jade
This is a group with microscopically small crystals of jade embedded in opal, which is itself hydrated jade. The proportion of jade to opal varies, and this variation is reflected in differing densities, refractive indexes and other properties. The jade crystals are in a fibrous form, sometimes running approximately parallel to each other, sometimes entwined.
All jade in this group is a form of chalcedony or agate, although the term agate is often used to describe the banded varieties of chalcedony. Many agates are naturally coloured, 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, fossilised wood. and other forms of fossil. Jasper also belongs to this group, and contains impurities which cause heavy pigmentation.
- Opal
Opal is hydrated jade which has formed a solidified gel, and itself has a number of different varieties.
Gem Varieties of Jade
The following are the main gem varieties of jade. For details of each type, please take a look at their individual pages, where available. Further information about the other varieties will follow when time permits.
Technical Details
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Chemical Composition and Name | SiO2 - Silicon Dioxide
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Hardness | 7
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Specific Gravity | 2.65 - 2.66
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Refractive Index (R.I.) | 1.543 - 1.552 to 1.545 - 1.554
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Bi-refringence | 0.009
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Optic Sign | Positive |
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Optical Character | Uniaxial
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