Greenstone is a collective name for hard, green-coloured rocks formed by metamorphism (transformation under high pressure and temperature) from volcanic rock. The green colour comes from minerals such as chlorite, epidote and actinolite that form during the transformation.
Characteristics
- Colour — grey-green to dark green, sometimes veined
- Hardness — hard and dense, wear-resistant and barely porous
- Origin — metamorphic rock (greenschist and related types), often from hill and mountain regions
- Weather-resistant — resistant to frost and wear
Application
Greenstone is used mainly where hardness and durability count:
- Paving — setts, cobbles and blocks for roads and squares
- Hydraulic engineering — armour stone for banks and dike revetments
- Masonry — rubble stone and hewn blocks in old buildings
- Decorative surfacing — chippings and decorative gravel
Greenstone is one of the harder types of natural stone and has been quarried for centuries where it reached the surface. In north-west Europe it is known mainly as an imported stone for paving and water works.
Related Terms
- Natural stone
- Metamorphic rock
- Rubble stone
- Basalt
- Greywacke
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