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Geologists use several
tests to identify minerals,
such as hardness (how easily a mineral scratches), specific
gravity (comparing a mineral's density to the density of
water), streak
(the colour of a mineral's powder), lustre (the way light
reflects off the surface), transparency (whether light can
pass through or not) and colour (some minerals have a
distinctive colour in natural light). Dropping acid onto a
sample to see if gas is given off is a simple test that can
be carried out in the field. You can also try simple
versions of two tests that geologists use. They will help
you identify some samples samples that you have collected.
Firstly, rubbing a rock on to the back of a tile leaves a
streak
mark &endash; the
colour of the streak can reveal what minerals are present.
Then you can calculate the specific gravity of a sample.
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