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What is Jade?
An ornamental stone, jade is
a name applied to two different silicate minerals. Nephrite is a form
of the amphibole actinolite (a mineral that also includes a form of asbestos).
The second, the mineral jadeite, is a pyroxene. Nephrite has the formula Ca2(Mg, Fe)5Si8O22(OH)2. Jadeite has the formula NaAlSi2O6.
The two are quite similar in appearance and it wasn't until 1863 that the two forms of this gemstone were distinguished.
It is an exceptionally tough material, and was first used for things
such as axe heads, knives, and weapons. Later, as other materials could
replace jade as a weapons material, it became appreciated for its beauty.
Jade has a Mohs hardness of between 6.5 and 7.0.
Nephrite can be found in a creamy white form as well as a green color, while
jadeite shows more color variation. Of the two, jadeite is rarer, and is the
form of jade mostly used in Central America. Nephrite jade was used mostly
in China, Myanmar and New Zealand.
Source:
http://en.wikipedia.org/wiki/Jade
What is bronze?
Bronze is the traditional name for a broad range of alloys of copper.
It is usually copper with tin as the main additive. First used during
the Bronze Age, to which it gave its name, bronze made tools, weapons
and armor that were either harder or more durable than their stone and
copper predecessors. During the Bronze Age, arsenic was often included
in the bronze (mostly as an impurity), which made the alloy even harder.
The earliest bronzes date to the late 4th millennium BC, and are found
in the context of Susa and some ancient sites in Luristan and Mesopotamia.
Source:http://en.wikipedia.org/wiki/Bronze
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