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Chalcedony
This wide collection of hard, colored, vitreous to
opaque stones (jaspers), is very famous since antiquity.
names like Red jasper, Blood Stone, Chrysoprase,
Petrified Wood,
Carnelian and Agates are just to list few from this big family of
stones used by the Greeks and the Romans in cameos to
celebrate their famous faces.
technical/details
SiO2 - Silicon Dioxide
Agate, like Chalcedony,
is a variety of quartz gemstones composed of layers of
quartz, sometimes of different colors. Agate usually
occurs as rounded nodules or veins in rock such as
volcanic lava. The layers of quartz are often
concentric. The composition of agate varies greatly, but
silica is always predominant, usually with alumina and
oxide of iron. Agate comes in most colors. There are
several types of agate. Common ones are: blue lace
agate, moss agate, tree agate and petrified wood.
Care and Treatment
Since agate is porous, it
is often dyed to enhance its natural color. Often
treated agate is sold as Black Onyx.
Petrified wood is
fossilized wood that has had its organic matter replaced
by agate.
Hardness
Agate will chip and crack
rather easily though it has a hardness rating of 7.
Specific Gravity: 2.65 -
2.66 |
