Page 24 - Curriculum Visions Dynamic Book

Jade and the chain silicates
It is more common for silica Jade
molecules to form long chains, similar to the polymerisation that allows simple organic molecules to be formed into plastics.
makes it suitable for carving. It is formed under conditions of high temperature and pressure deep
Chain silicates are among the
most common minerals. They are
very strong in the direction of the green mineral, which is what
chain, but they are much weaker
between chains. This means that they
tend to break parallel to the chains. within mountain systems and so
Pyroxenes and amphiboles
The pyroxenes are an extensive group of minerals. Not only do they form in nature, but they also form in many industrial processes. For example, the slag produced during the refining of iron ore in a blast furnace often has the mineral composition of a pyroxene.
Pyroxenes are the major component of basaltic lava, the most common rock
at the Earth’s surface (it underlies
all the world’s oceans). Thus,
pyroxenes though not widely known, are among the most common minerals.
The most frequently seen pyroxene mineral, augite, is dark green to black.
Amphibole has
the same chemical
composition as the
pyroxenes, but it forms
at a lower temperature.
The most common mineral
of this group is hornblende, a
dark green to black mineral found in all basalts.
Because most basalts cool quickly, only
small crystals form in them, so it is usually very difficult to distinguish between the pyroxenes and amphiboles, as both look like small, dark crystals.
 The main use for jade is in the art of the Far East. It was once used to make massive objects such as state coaches. The jade on this detail of a state coach weighs many tonnes.
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Jade is a gemstone that is especially highly regarded in Asia. It is a combination of a chain of silica molecules with sodium and aluminium. The green colour is produced by atoms of iron.
Jade does not occur as crystals, but rather as large lumps of
is a mineral of metamorphic rocks.
 Augite.