Loanhead Quarry, Beith, North Ayrshire, Scotland, UKi

Regional Level Types
Loanhead Quarry	Quarry (Active)
Beith	- not defined -
North Ayrshire	Council Area
Scotland	Country
UK	Country

Loanhead Quarry is situated near the A737 road, about 2 km (over 1 mile) north of the village of Beith, which is about 20 km (12.5 miles) from central Glasgow.

The north-eastern part of the quarry is active and operated by Tarmac Roadstone (Scotland) Ltd. Since 2012 W.H. Malcolm Limited has had the landfill site (within the south-western part of the quarry) operating to infill the quarry void with inert soils. Active quarrying is separated from the landfill area by a rock wall feature (dolerite dyke) approximately 15m wide.

In Lower Carboniferous times (about 360 million years ago), the Glasgow area was subjected to intense and widespread volcanic activity. Basic lava flows and volcanic ash were poured out over an area of more than 2500 km' reaching a maximum thickness of 800 m, and these are known as the Clyde Plateau Lavas. They now form the flat-topped Campsie Fells, Kilpatrick Hills and Renfrew Heights lying to the north, west and south of Glasgow respectively. Loanhead Quarry is excavated in the basalts which form the high ground to the SW of the city. Three successive lava flows can be seen in the quarry, although the continuous removal of rock from the faces may make them difficult to identify from time to time.

Most of the interesting minerals in the basalt lavas are not primary minerals, originally crystallising as an integral part of the rock, but secondary minerals formed in the vesicles and joints of the basalt after it had consolidated. The most common mineral is calcite, found as 'dog-tooth' crystals, cleavage rhombs and as massive aggregates. Pale green, botryoidal (grape-like) masses of prehnite are common, and also snow-white crystals of analcime. Copper may be found native on joint surfaces and also as the hydrated carbonate malachite, and the oxide cuprite. Zeolites are present though rather rare, especially red heulandite, and the white fibrous minerals thomsonite and natrolite. An important collection of the zeolite minerals of the Glasgow district can be seen in the Hunterian Museum of Glasgow University.

As regional vulcanicity waned, hot waters, perhaps bearing carbon dioxide, percolated through the consolidated lava pile. The existing primary minerals (olivine, feldspar, augite) were altered, and elements released during this episode contributed to the formation of low-temperature secondary minerals such as calcite and zeolites in the cavities and fissures of the basalts. Either copper was magmatic in origin, or it was formed by the percolating waters concentrating the minute quantities of copper originally found in the basalt.

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References