Wheal Unity, Gwennap

Overview

One of the richest copper mines drained by the Great County Adit in Gwennap, which made over £100,000 profit in 1792-98, was 144 fathoms below adit with three engines by 1819, and was worked with Poldice from the early 1800s.

History

Wheal Unity was a copper mine in the parish of Gwennap, near St Day, worked beside Poldice in the heart of the district's copper ground. By 1792 a branch of the Great County Adit, the drainage tunnel begun from the Carnon valley in 1748, had been driven from Poldice to Wheal Unity, and the cheaper pumping that came with it helped make Unity one of the richest of the mines the adit served. From 1792 to 1798 the adventurers' share of its ore, after dues, was worth £197,573, and it returned a profit of £101,604.

By 1819 the mine had been sunk 144 fathoms below the deep adit and was worked by three steam engines, of 60, 58 and 52 inches. Early in the nineteenth century it was merged with Poldice, and Poldice's copper returns from 1819 into the 1830s were recorded together with Unity's. Its workings were later drawn on plans with Creegbrawse, and with Wheal Maiden as part of St Day United, and it was among the Gwennap mines whose district plan was lodged as abandoned in 1866.

Geology

Copper lodes of the Gwennap district, drained by the Great County Adit.

Workings

Drained by a branch of the Great County Adit from Poldice by 1792; sunk 144 fathoms below the deep adit with three steam engines of 60, 58 and 52 inches by 1819.

Closure

Merged with Poldice in the early nineteenth century and later worked within St Day United; named on a Gwennap district abandonment plan of 1866.

What remains

Unknown.

Related mines

• Great County Adit — A branch of the Great County Adit was driven from Poldice to Wheal Unity by 1792, draining the mine and cutting its pumping costs.
• Poldice Mine — Wheal Unity was drained by a branch of the Great County Adit from Poldice by 1792 and merged with Poldice early in the nineteenth century.

Recorded claims

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

• By 1792 a branch of the Great County Adit had been driven from Poldice to Wheal Unity. ¹
• From 1792 to 1798 the adventurers' part of the ore was worth £197,573, and the mine made a profit of £101,604. ²
• By 1819 Wheal Unity was 144 fathoms below the deep adit, with steam engines of 60, 58 and 52 inches. ²
• Early in the nineteenth century Wheal Unity merged with Poldice, whose returns from 1819 were recorded with Unity's. ³
• Its workings appear on plans with Creegbrawse and with Wheal Maiden as part of St Day United, and on a Gwennap district plan of 1866. ^4,5,6

Sources

1. (secondary) Great County Adit — Wikipedia
2. (secondary) Wheal Unity Mine, Cornwall (Cornwall Calling) — Cornwall Calling
3. (secondary) Poldice mine — Wikipedia
4. (primary) BGS mine plan: WHEAL UNITY AND CREEGBRAWSE, copper ore — British Geological Survey / Mining Remediation Authority
5. (primary) BGS mine plan: ST. DAY UNITED WHEAL MAIDEN WHEAL UNITY, tin and copper ores — British Geological Survey / Mining Remediation Authority
6. (primary) BGS mine plan: GWENNAP (DISTRICT) CLIFFORD SOUTH CONSOLS POLDICE UNITED WHEAL MAIDEN WHEAL ST. AUBYN WHEAL UNITY, abandoned 1866 — British Geological Survey / Mining Remediation Authority

Record created: 18 October 2026 · Last researched: 25 October 2026