Tardree Quarry

Overview

A disused quarry on the south side of Tardree Mountain, in central County Antrim, cut into the rhyolite of the Tardree Rhyolite Complex, the largest body of this rare rock in the north of Ireland. Its columnar-jointed grey rhyolite was worked for local building stone and paving. The quarry is now protected as an Area of Special Scientific Interest for the tiny tridymite crystals in its cavities.

History

About 60 million years ago, during a lull between the eruptions of the Lower and Upper Basalts of the Antrim Lava Group, the Tardree volcano erupted silica-rich rhyolite lava, tuff and obsidian across about ten square miles of central Antrim. Rhyolite has a composition close to granite but cooled quickly at the surface, and it is uncommon in the north of Ireland. A guide of 1902 described the quarry on the south side of Tardree Mountain as the main exposure of the rock. There the rhyolite is grey, compact and without banding, and its well-marked columnar jointing made it easy to quarry. It was used locally for building, the smaller blocks for paving. Tardree rhyolite appears in buildings across County Antrim as rubble, quoins and dressings, alongside the local basalt; it weathers by scaling. A second quarry, north-east of the mountain, worked a less compact rock. The mineralogist Lasaulx noted tridymite in small cavities in the rhyolite at this locality in 1880. When the quarry was surveyed for the Earth Science Conservation Review in 1997 it was disused and used for dumping farm, building and household waste. It was recommended for conservation and is now an Area of Special Scientific Interest.

Geology

Rhyolite of the Tardree Rhyolite Complex, in the Interbasaltic Formation of the Antrim Lava Group (Palaeogene). Grey, compact and columnar-jointed, with phenocrysts of sanidine, plagioclase and quartz, and small drusy cavities lined with tridymite crystals 1 mm or less long.

Workings

An open quarry face in columnar-jointed rhyolite.

Closure

Working dates are not recorded in the sources read; it was described as the main working exposure in 1902 and as a disused quarry in 1997.

What remains

Disused; in 1997 the quarry was being used for dumping waste and becoming overgrown.

Quarry faces showing columnar jointing, and spoil.

Redevelopment

None; an Area of Special Scientific Interest, reached by a farm lane.

Related mines

• Tievebulliagh Axe Factory — Both Antrim interbasaltic sites where the ESCR records tridymite: in cavities at Tardree, in baked rock at Tievebulliagh.

Recorded claims

Individual factual claims, each attached to the source(s) that support it below. Where sources disagree, both are kept.

• The main exposure of the Tardree rhyolite is the quarry on the south side of Tardree Mountain; its columnar jointing readily allows quarrying, and the rock was used locally for building, the smaller blocks for paving. ¹
• In 1997 the site was a disused quarry on the south side of Tardree Mountain, used for dumping waste, and was recommended for conservation. ²
• Lasaulx recorded tridymite in small vuggy cavities in the rhyolite at the locality in 1880; the crystals are generally 1 mm or less long. ²
• The Tardree Rhyolite Complex formed during interbasaltic times and is the largest and best-exposed rhyolite in the north of Ireland. ^3,2
• Tardree rhyolite is used as building stone throughout County Antrim as rubble, quoins and dressings, and weathers by scaling. ⁴

Photographs & further reading

Sources

1. (secondary) A Guide to Belfast and the Counties of Down and Antrim (1902): Geology — Belfast Naturalists' Field Club guide, 1902 (transcribed by Eddie's Extracts)
2. (primary) Tardree Mountain (Earth Science Conservation Review site 524) — National Museums NI / Earth Science Conservation Review (R. Nawaz and N.R. Moles)
3. (primary) Antrim Lava Group, Palaeogene extrusive igneous rocks, Northern Ireland — British Geological Survey (Earthwise)
4. (secondary) Tardree Rhyolite — Stone Database NI

Record created: 18 September 2026 · Last researched: 18 September 2026