Page 23 - Curriculum Visions Dynamic Book

 Aquamarine.
igneous rock: a rock that has solidified from molten rock, either volcanic lava on the Earth’s surface or magma deep underground. In either case the rock develops a network of interlocking crystals.
metamorphic rock: formed either from igneous or sedimentary rocks, by heat
and/or pressure. Metamorphic rocks form deep inside mountains during periods of mountain building. They result from the remelting of rocks during which process crystals are able
to grow. Metamorphic rocks often show signs of banding and partial melting.
Aquamarine
Aquamarine is a clear form of beryl that is regarded as a gemstone. The blue–green colour comes from the elements chromium and iron.
 Tourmaline.
Tourmaline
Tourmaline is a silicate
compounded with
boron. (This is the
same chemical unit
that makes some
glass heat-resistant.)
It commonly forms
black needle-like
crystals in igneous
rocks, especially granites.
The faces of the crystals
have scratches (striations)
on them that make the surface
look like a piece of a record.
The crystals are hard and have a glassy lustre. One form of tourmaline becomes electrically charged when its temperature is changed.
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