Page 12 - Curriculum Visions Dynamic Book

Minerals containing sulphur
Sulphur, being a reactive element, occurs in combination with a wide range of other elements. Most of these compounds are sulphides, often known as pyrites. If the compounds also include oxygen, they
are known as sulphates.
Most sulphides feel heavy because they
contain heavy sulphur atoms densely packed inside the minerals. Most of the sulphides are either brassy-coloured or dark, and some are very distinctive. For example, cadmium sulphide is bright orange (page 25).
Pyrite (iron sulphide), is perhaps the best known of the sulphides. Pyrite can be used
as an iron ore (a rock that contains useful amounts of metal). Other main sulphur ores include galena (lead sulphide), sphalerite (zinc sulphide) and chalcopyrite (copper sulphide).
Many of the world’s most important ore bodies are sulphides. The huge open-cast mine at Bingham, Utah, USA – claimed
to be the world’s largest man-made hole – has been dug into veins of copper sulphide.
The molybdenum mine at Climax, near Leadville, Colorado, USA, is also made from many veins of sulphide ore. When at its peak,
it produced 80% of the entire world’s supply of molybdenum. In Sudbury, Ontario, Canada, there are also large deposits of copper and nickel sulphides.
Sulphur is also found in calcium sulphate (as gypsum – used for Plaster of Paris and
wall boards) and barium sulphate (as the
very heavy mineral barite).
 Many crystals can form part of the cubic crystal system. Pyrite normally forms simple cubes, as shown above.
 Lead sulphide, or galena, is a common mineral, found in places that have experienced volcanic activity. It is associated with zones from which miners collect other ores such as silver and tin.
It is easily spotted by its dark grey cubic (box-shaped) crystals. It is also found in limestone and dolomite rocks through which heated waters have passed.
Galena is a soft mineral. When it is rubbed against a surface it leaves a grey streak of colour, showing its lead content. It is a very heavy mineral and the main source of lead for the world’s industries.
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