Glossary
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QPA
See Quarry Products Association.
Quarry Products Association (QPA)
Quarry Products Association. The QPA represents the interests of more than 120 quarry operators who together produce more than 90% of the UK's aggregate-based construction materials and in doing so provide livelihoods for 40,000 people.
www.qpa.org
Quartz
One of the most common rock-forming minerals, usually found as a colourless and transparent crystalline silica, although it can be coloured if impurities are present. Its hardness and lack of cleavage make it resistant to abrasion, so it is an important constituent of sedimentary rocks.
Quartzite
A sandstone composed of quartz grains cemented by silica.
Quaternary
The latest geological period, covering 2 Million years ago to the present, representing the last part of the Cenozoic era. The Quaternary can be subdivided into two epochs; the Pleistocene (two million years to ten thousand years ago) and the Holocene (ten thousand years ago to the present day).