Masson Hill Quarry, Matlock, Derbyshire Dales District, Derbyshire, England, UKi

Regional Level Types
Masson Hill Quarry	Quarry (Reclaimed)
Matlock	Town
Derbyshire Dales District	District
Derbyshire	County
England	Constituent Country
UK	Country

Mining has been active around Matlock, Derbyshire, from medieval times to the present, firstly for lead and more recently for fluorspar. Amongst the more important areas has been around the summit of Masson Hill, which has been intensely mined for fluorspar throughout the 20th century. Masson Hill itself is a prominent topographical feature, rising to 335 m, and situated 1.5 km west of Matlock. The mineralisation consists of a series of intermittent smaller flats and/or pipes over a distance of 1500 m. The largest single flat worked (or more strictly a pipe since the strike length was greater than its width along the dip) was that at the site of Masson Opencast Quarry, having a strike length of greater than 500 m and width of 240 m. The main ore horizon was restricted to the basal 6 m of the Matlock Lower Limestone (Lower Carboniferous, Brigantian Age), although mineralisation was found to occur above this within the overlying dolomites of the same formation. The basal limestone at the locality is thickly bedded and poorly jointed, containing noticeable fossil debris and with calcite veining.

Mineralogically, the ore consists of approximately 60% fluorite, 20% quartz, 15% calcite and less than 5% baryte, and traces of galena, sphalerite and other sulphides. It occurs as replacements of the limestone and as open space infilling, and is a direct result of the interaction of a number of geological processes. The fluorite is normally colourless to pale yellow, less often it is blue, green, or purple, the last colour being especially common at the crystal edges or surfaces near to other minerals, especially baryte and smithsonite. Cubic crystals are common. Three types of inclusions in the fluorite occur: the relict sedimentary carbonates and quartz within; fluid inclusions; and primary sulphides common to all fluorites. The most common inclusions are bravoite, pyrite, marcasite, and chalcopyrite.

In the early 30s there was, for a short time, up to ten limestone quarries in production along the Derwent Valley between Matlock Bath and Darley Dale. All were eating into the base of Masson Hill, whilst to the south and west (at Cromford, Bonsall and Ible) there were other quarries nibbling at the same hill.

In 1935, Derbyshire Stone Ltd was formed to bring together the quarrying assets of several local companies.

From 1939 to 1945, the growing demand for minerals caused hitherto deserted lead mines to be explored and reopened for the winning of gangue minerals. Old tips and hillocks were removed even though the quality was low grade. This demand for crude ore continued long after the war to enable rebuilding. The wartime production at the summit of Masson Hill was opencast, limestone being crushed in a mill at the site or taken to Derbyshire Stones primary crushers at nearby Cawdor Quarry, whilst the minerals won were taken to the mineral processing plant at Megdale, sited just above Cawdor Quarry.

After the war (and into the 1960s) fluorspar, baryte, calcite, the lead/zinc ores, sands and gravel and of course coal, all had a great future in Derbyshire.

In 1968, Tarmac acquired Derbyshire Stone Ltd and continued with quarrying operations. The large opencast quarry at Masson Hill frequently broke into 18th/19th century old mine workings.

Beneficiation of fluorspar was carried out at Cavendish Mill, near Eyam, operated by Laporte Industries Ltd. Opened in 1965, Cavendish Mill was designed to process ore from a variety of sites throughout the Derbyshire Orefield, including Masson Opencast. At one stage Cavendish Mill was one of the largest and most efficient fluorspar processing sites in Europe.

However, diminishing reserves of ore eventually resulted in quarrying operations at Masson Opencast gradually coming to an end during the 1970s. Many of the quarries in the area also ceased operating due to cheaper imports. By August 1979, the large hole at Masson Hill, originally excavated by Derbyshire Stone Ltd and subsequently run by Laporte Industries Ltd, had been back-filled to original contours and by 1980 the surface of the site had been cleaned up and landscaped, although a section of the opencast was left open so as to preserve geological features.

In the 1980s, Laporte disposed of its manufacturing operations due to loss of their business to foreign imports. Despite the cessation of fluorspar processing by Laporte, Glebe Mines was established in November 1999 to continue the processing business based at Cavendish Mill because U.K. users of acid grade fluorspar still wished to use the high quality Derbyshire material.

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