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Mineral Identification

mineral specimen glowing green and orange under ultra violet light

There are over 4000 different minerals.

 Some of them are instantly recognisable, but many can look very similar. So how do you tell them apart?

There are a few tests that you can do to find out a minerals identity.

Minerals with distinctive colours

Some minerals exhibit particular colours that make them easier to recognise.

 
Yellows and golds examples Reds and oranges examples
Purples and blues
examples
Greens examples

Gold: gold, pyrite, chalcopyrite

Yellow: sulphur, carnotite
Yellow-green: autunite
Rose red: rhodonite
Red wine: cuprite
Ruby red: ruby
Marmalade: citrine
Purple: amethyst
Blue: azurite, lazulite
Sky blue: sapphire

Opaque green: malachite, varsicite

Jade green: jageite, nephrite
Clear green: emerald, olivine

Mohs Scale of Hardness

The Mohs scale of hardness was created by Friedrich Mohs a German mineralogist in 1812. When mineralogists talk about hardness, they mean scratch hardness- the minerals resistance to being scratched.

The Mohs scale arranges minerals from 1 to 10. 1 is Talc and 10 is Diamond. Diamond is the world’s hardest mineral. In the original Mohs Scale, ten minerals were arranged in order of increasing hardness and were assigned the numbers one to ten. These ten minerals are shown here:

 
Mohs mineral Mohs Number Can be scratched by Simple Classification
Talc 1   soft
Gypsum 2 Fingernail soft
Calcite 3  'Copper' coin medium
Fluorite 4 Iron nail medium
Apatite 5  Knife blade or glass medium
Orthoclase (feldspar) 6
 penknife
hard
Quartz 7 Steel file hard
Topaz 8  Sandpaper hard
Corundum (emery) 9  Knife sharpener hard
Diamond 10   hard

Glow in the Dark

Some minerals glow in the dark!   The minerals appear to glow when these different types of light are shone onto them. This glowing effect is called fluorescence. The word fluorescence is taken from the mineral fluorite, which usually glows a bright purple/blue under UV light.

View this mineral in 3D

 

Photograph reproduced with the kind permission of the Geevor Archive

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Comment left by mineral man on 2010-06-29 15:34:14

i like pictures

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