Page 10 - Curriculum Visions Dynamic Book

Crystals of sulphur
Sulphur provides striking and colourful crystals.
All crystals form in one of seven categories, known
as the crystal systems. Some elements, such as sulphur, can form crystals in more than one crystal system.
Sulphur produces bright yellow crystals in the monoclinic system (where crystals look like double-ended chisel blades) and amber crystals in the rhombic system (where crystals look like three-dimensional parallelograms, like a matchbox whose base has been fixed while its top has been pushed sideways).
Brimstone is also pure sulphur, but it is not in crystalline form. It is formed as bacteria consume hydrogen sulphide gas in environments with no oxygen.
 To produce these beautiful chisel-like monoclinic crystals, sulphur was dissolved in hot methyl benzene and the dissolved yellow solution allowed to cool. A hot solution can contain more resulting material than a cool solution, so as the solution cools, it reaches a temperature at which the solution cannot contain any more sulphur (it is a saturated solution) and some of the sulphur begins to form into a solid. The growing crystals act as a focus for the deposition of more sulphur in the cooling liquid, so the crystals continue to grow.
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