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Quartz is the most common of all minerals. It consists of silicon dioxide
and is found in many rocks, particularly acid igneous rocks such as granite
and metamorphic rocks such as gneisses. It is also found in sand and gravel,
which form sandstone when consolidated. Quartz typically occurs as
colourless or white hexagonal prisms. The colourless form is the purest and
known as rock crystal, often used as imitation diamonds. But quartz is also
used as a gemstone when coloured by impurities. For example: amethyst
(violet-purple), rose (pink), citrine (yellow) and brown (cairngorm). Uncut
clusters of rock crystal as pictured here are very popular and found in many
parts of the world including the Alps - but are very difficult to discover.
Many crystal prospectors spend a lifetime searching the “innards” of
mountains with hammer, chisel and crowbar to uncover these natural
treasures. |
