Esgair Hir and Esgair Fraith Mines

Overview

Esgair Hir and Esgair Fraith, two lead mines worked together on the same vein north of the Nant-y-Moch reservoir, were acclaimed in their day as 'the richest in all Wales' — the Welsh Potosi — and their 1689 legal battle with the Crown helped open up private mining across the country.

History

An ore outcrop at Esgair Hir was discovered before 1690, and the estate's owner, Sir Carbery Pryse, began working it himself — directly challenging the Society of Mines Royal's royal monopoly over gold- and silver-rich mines. The courts ruled in Pryse's favour, letting him form a company and mine freely, a victory that opened up private capital and new mines across Wales more broadly. The Company of Mines Adventurers of England worked the site from 1703 to 1708, raising around 2,000 tons of ore. After long fallow periods and lesser attempts in 1760 and 1788, Williamson & Eyton took on the mine in 1839, spending the winter of 1839-40 building four and a half miles of road to it and installing large pumping machinery; that phase lasted until 1848. The Welsh Potosi Company that followed built new surface structures and steam engines, but its miners struck over unpaid wages in 1856 and the company failed in 1857. Cardigan Consols worked the site from 1858 to 1867, concentrating on shaft development with little ore to show for it, and a series of small, undercapitalised partnerships stripped what remained of the old workings between 1886 and 1904, when the mine finally closed for good — defeated, as so often, by its remote mountain location, chronic undercapitalisation, and falling ore prices.

Geology

Esgair Hir and Esgair Fraith lie on a mineralised fracture zone, up to 60ft wide in places, running east-west along the Ordovician-Silurian boundary and traced for some 4km; lead ore occurs in vertical pipes that narrow with depth, with copper content rising and lead falling toward Esgair Fraith to the east.

Abandoned workings can be dangerous — unstable ground, uncapped shafts, flooding and bad air are common even where a site looks safe from the surface. This entry describes history and general location only; it is not an access guide.

Recorded claims

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

• Sir Carbery Pryse's decision to work the ore outcrop at Esgair Hir himself, discovered before 1690, directly challenged the Society of Mines Royal's monopoly over precious-metal mining; the courts ruled in his favour, a victory that helped open up private capital and new mines across Wales. ¹
• The Company of Mines Adventurers of England worked Esgair Hir and Esgair Fraith from 1703 to 1708, raising around 2,000 tons of ore. ¹
• Williamson & Eyton, who took on the mine in 1839, spent the winter of 1839-40 building four and a half miles of road to reach it, and installed large pumping machinery, working the site until 1848. ¹
• The Welsh Potosi Company's miners struck over unpaid wages in 1856, and the company failed the following year. ¹
• A series of small, undercapitalised partnerships stripped what remained of the old workings between 1886 and 1904, when the mine finally closed for good. ¹

Photographs & further reading

This page doesn't try to reproduce everything — these are the best original sources found for this mine.

Images

Sources

1. (secondary) Esgair Hir & Esgair Fraith Mines — Northern Mine Research Society

Record created: 20 August 2026 · Last researched: 20 August 2026