Milldam Mine

Overview

The last underground fluorspar mine in Derbyshire, driven into the Hucklow Edge vein from Great Hucklow. An old lead mine reopened in 1985 to work the fluorspar its lead miners had thrown away, it stopped production in October 2023 and sits on care and maintenance, waiting for the price to come back.

History

The old Mill Dam Mine at Great Hucklow was a lead mine, worked until 1885. What its miners discarded as waste — fluorspar and baryte — was what brought mining back a century later: the mine reopened in 1985 under Laporte Minerals to rework the Hucklow Edge vein for fluorspar, with baryte, lead and zinc as by-products. Planning consent to continue underground mining was granted for fifteen years in 1999, but only a little extraction followed; the mine spent most of that consent on care and maintenance until new owners British Fluorspar restarted work in the autumn of 2012. Production ended again in October 2023, when Fluorsid British Fluorspar stopped mining at a loss.

Geology

Milldam works the Hucklow Edge vein system in the South Pennine orefield, where the mineralised vein runs through limestone capped by shale and gritstone. The workable depth of vein within the limestone is usually about 100 m, and its width varies sharply over short distances along strike — anywhere from 1.5 m to 15 m. The whole Hucklow vein structure has been estimated to hold around 2.4 million tonnes of fluorspar.

Geological setting: Hydrothermal Deposits (well documented example), Veins and Lodes (well documented example)

Workings

Access is not by shaft but by a 1-in-8 drift driven down from the mine compound on the edge of Great Hucklow, entered just below the exposed contact between the shale cap and the limestone beneath. Working progresses along the vein in blocks, with a crown pillar left to support the shale cap and prevent subsidence at surface, and ventilation and rise holes carried up as the workings advance. Ore is trucked out by a private haul road and taken to the Cavendish Mill processing plant at Stoney Middleton.

Closure

Fluorsid British Fluorspar ceased operations in October 2023 because the mine was running at a loss. Nearly all staff were made redundant, five being kept on for maintenance, and equipment was stripped out and sold to meet company debts.

What remains

On care and maintenance rather than abandoned, with the company stating it will reopen when world fluorspar prices make working viable again. Ground remediation continues in the meantime — refilling collapse holes along Hucklow Edge, with ground-penetrating radar survey planned and stockpiled material to be moved off the eastern boundary.

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.

• The workable depth of vein within the limestone is usually about 100 m, with vein width varying between 1.5 m and 15 m over short strike lengths; the Hucklow vein structure has been estimated to hold around 2.4 million tonnes of fluorspar. (high) ¹
• Access is by a 1-in-8 drift driven downwards from the Milldam compound at Great Hucklow, entered just below the exposed shale/limestone contact, with ore hauled to the Cavendish Mill at Stoney Middleton. (high) ¹
• A crown pillar support system holds up the shale cap to prevent subsidence, with ventilation and rise holes incorporated into the workings. (high) ¹
• The mine was largely unworked and on care and maintenance for much of its 1999 fifteen-year consent, until British Fluorspar recommenced work in autumn 2012. (high) ¹
• Operations ceased in October 2023 because the mine was running at a loss; five staff were retained for maintenance, equipment was sold, and the company said it would reopen when prices allow. (high) ²
• Milldam was the last working fluorspar mine in Derbyshire. (medium) ³

Photographs & further reading

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

Sources

1. (primary) Renewal of consent to continue underground mining of fluorspar, Milldam Mine — committee report — Peak District National Park Authority
2. (secondary) Milldam Mine: cessation of operations — Great Hucklow Parish Council
3. (secondary) Milldam Fluorspar Mine, Great Hucklow — Peak District Mines Historical Society

Record created: 25 August 2026 · Last researched: 25 August 2026