ESCR - Clinty Quarry - Mineralogy

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Clinty Quarry - Mineralogy	Antrim

Site number:	526
ESCC:	EA
Locality Type:	Quarry (working)	Status:	ESCR
Grid Reference:	D101071 Centroid
Google maps:	54.89987,-6.28375
County:	Antrim	Council area:	Mid & East Antrim Borough Council
Period:	Tertiary
Stages:	Eocene
Lithostrat:	Interbasaltic Formation, Upper Basalt Formation

Site Description
Clinty Quarry, near Ballymena, Co.Antrim: view of exposures near site office.
Highlights:
An active quarry in Tertiary basalt with zeolite minerals and Interbasaltic Beds of bauxite, laterite and lignite.
Introduction:
Clinty Quarry, located 4km north of Ballymena town centre, is a working basalt quarry operated by Robert Stevenson and Brothers Ltd. Also on the site is an industrial plant that produces ferrous aluminium sulphate solution (FAS) using lateritic bauxite from the quarry. Clinty Chemicals Ltd. market FAS as a flocculating agent and water purifier. Access to the quarry must be arranged through Stevenson’s: in previous years the managers have permitted educational and research visits. The quarry affords excellent exposures of the Interbasaltic Bed including a section with pisolitic ironstone and quarried sections showing profiles through the Beds and residual core-stones of basalt. Amygdaloidal basalts containing zeolites and calcite occur within the basalt quarry, and intermittently laterites with lignite are exposed.
Description:
There are three areas of interest at Clinty Quarry: (a) rock exposures close to the site offices; (b) the bauxite quarry; and (c) the basalt quarry. Area (a) is located within the site c.60m north of the main office (see map). It comprises an inclined road-cut and an adjacent 3m-high, 15m long cliff section exposing laterites of the Interbasaltic Bed and an overlying lava flow of the Upper Basalt Formation. Clinty Quarry, near Ballymena, Co.Antrim: flow top / laterite. The exposure is best on the east side of the road-cut, where the uppermost 1m-thick part of the Interbasaltic Bed contains layers of pisolitic ironstone. The black rounded pisoliths, typically 2-8mm in size, are magnetic and presumably comprise a mixture of hydroxides and oxides of iron including magnetite. The lowermost part of the overlying Upper Basalt Formation has a pillowed appearance, and a glassy (hyaloclastite?) layer is evident within the flow about 1m above the contact. Clinty Quarry, near Ballymena, Co.Antrim: bauxite workings. Area (b) is the lateritic bauxite quarry located at the north-west side of the main quarry. The uppermost 2m of the Interbasaltic Bed is the best quality material for FAS production, and in 1997 an area of c.30m by 30m had been cleared of overburden (including previously worked ‘quarry fines’) prior to extraction. Clinty Quarry, near Ballymena, Co.Antrim: bauxite close-up. Of geological interest are vertical sections through the Interbasaltic Bed that show a variety of colours and textures, and residual core-stones of basalt. These occur as ‘giant’s eyes’ within the bauxite, and as metre-diameter rounded boulders that have been separated out and stockpiled during quarrying operations. Area (c) is the main basalt quarry, which in 1997 was active in the northern section while the southern workings were disused and had become overgrown. The quarry is worked in the 15-20m thick, massive lower flow of the Upper Basalt Formation, and zeolite-bearing amygdaloidal material is fairly scarce. Saponite-filled pipe amygdales were noted in loose material, and towards the southern end of the active area, amygdaloidal basalt containing zeolites and calcite. Clinty Quarry, near Ballymena, Co.Antrim: thomsonite and natrolite in fresh basalt. Zeolites include thomsonite, natrolite, mesolite, analcime, chabazite and gyrolite, and apophyllite has also been found. On occasions when quarrying has inadvertently cut into the underlying Interbasaltic Bed, lignite has been found in the form of tree trunks and roots in situ within the lateritic bauxite.
Importance:
Features seen here are not unique in Northern Ireland: similar features occur on the currently inaccessible cliff path east of the Giant’s Causeway. However, the Clinty Quarry site is worthy of designation for several reasons: (a) its accessibility; (b) the variety of features that can be seen in a small area; and (c) the economic use of the laterite which is of educational value as this links geology, chemistry and environmental sciences.
Interpretation:
The vertical sections through the Interbasaltic Bed allow rock weathering and laterite development to be demonstrated. Comparisons can be made with regions of present-day lateritic soil development such as Australia, where pisoliths commonly form the ground surface and are underlain by laterites and deeply-weathered rock. Hill et al. (2000) report recent research on the Eocene laterites of Northern Ireland and conclude that a sub-tropical climate with high rainfall resulted in formation of the Interbasaltic Bed over a relatively short period of time (1-2 million years). This contrasts with the laterites in Australia and other relatively arid countries which are thought to have developed over a time period of at least 50-60 million years.
Conclusions:
Clinty Quarry is a high priority site for designation on the basis of mineralogical, palaeo-environmental and economic interest.
Notes:
See also SLNCI Key Site 712 - Clinty Quarry.

Keywords
Minerals:	Analcime, Calcite, Chabazite, Gyrolite, Natrolite, Saponite, Thomsonite, Zeolites, Mesolite, Apophyllite
Rocks:	Amydaloidal Basalt, Basalt, Bauxite, Ironstone, Laterite, Lignite
Structures:	amygdales, pipe amygdaloid
Paleoenv:	subtropical

Access
Management:
The exposures in area (a) are relatively secure in that active quarrying is unlikely to occur in this area, but the quarry management should be aware of their interest to ensure that the outcrops are conserved. Active extraction continually refreshes exposures in the quarry, however should extraction of laterite in area (b) cease, provision should be made to retain a representative section for future access.
Uses
Uses:	The site is an active quarry, and part of the area of interest comprises exposures in a now inactive area of quarry. The surrounding area is farmland and forestry.


Map(s):	OSNI 1:50,000 sheet 9.
Record type:	ESCR report	Recorded by:	R. Nawaz and N.R. Moles
Entered by:	E M Porter
Last updated:	07 MAY 68

Enlander, I., Dempster, M. & Doughty, P., 2026. Clinty Quarry - Mineralogy, County Antrim, site details. [In] Earth Science Conservation Review.
https://www.habitas.org.uk/escr/site.php?item=526. Accessed on 2026-11-06.

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