Though the Askrigg Block mineral deposits have never produced the quantities of ore or the quality of specimens that have come from further north, North Yorkshire has seen considerable mining activity, primarily for lead, during the 18th and 19th centuries. Mineral zonation is less well developed than within the Alston Block, but several areas do show concentrations of fluorite, along with barite as gangue. Unlike fluorite from the Alston Block to the north, fluorite from North Yorkshire is not strongly fluorescent, and twinning if relatively rare. Colors are generally restricted to pale yelow and purples, as well as colorless.

A handful of deposits have been found contained enough fluorite to allow commercial development for fluorspar – albeit briefly – during the 20th century. Chief among them is the Gillheads Mine in Wharfdale. A good summary of the mining history in North Yorkshire can be found in Symes & Young (2008).


A map showing the location of important mines in North Yorkshire. Map by Peter Briscoe.






Swaledale and Arkengarthdale

The area between Swaledale and Arkengarthdale to the west of Reeth is perhaps the most heavily mineralized region in the Askrigg Block, with numerous old mines, prospects, hushes, and quarries dotting the landscape. The Old Gang Mines are a series of workings on the Friarfold and Old Rake veins, north of the village of Gunnerside. While these deposits have been worked primarily for lead, Dunham (1952) reports appreciable amounts of barite, witherite, and fluorite being present in mine tailings.

In Arkengarthdale, just west of Langthwaite the Justice Level accesses a complex of veins that were worked for lead in the 19th century. Barite and fluorite are also common in these deposits, and several old hushing scars expose the veins at surface. In recent years specimens of amber/yellow fluorite associated with barite have been recovered from the level by local collectors.


Workings at the Justice Level, near Langthwaite, Arkengarthdale, seen in 2007. Photo courtesy of John Lawson.


A group of yellow fluorite crystals with associated barite with minor sulfides included in the fluorite. 6 cm across. From the Justice Level, Arkengarthdale.

In remote upper Swaledale west of the village of Keld a number of trials for lead and copper minerals were made during the 18th and 19th centuries on the Keldside veins at Great Sleddale. Although it does not appear that these deposits were ever worked commercially, specimens of amber fluorite have been recovered from cavities on the veins, as well as some copper minerals including azurite, malachite and chrysocolla.


A group of amber-yellow fluorite crystals on ironstone matrix. 9 cm across. From the Keldside Vein, Great Sleddale, upper Swaledale.


The East Arn Gill Mine is located 1.2 km north of the village of Mucker, on the east side of Arn Gill, a tributary to the River Swale. The mine is accessed by the Adelaide and High Levels, and work for lead was done for a few years around 1865, and again in 1918-1920. Dunham and Wilson (1985) mention the existence of flats at the mine, and a number of good specimens of amber/yellow fluorite associated with galena are in the Russell collection at the NHM London.


A group of yellow fluorite crystals with associated galena (likely coated with hydrocerrusite), from the Arn Gill Mine, near Mucker, North Yorkshire. Approximately 8 cm across. Sir Arthur Russell collection, now in the Natural History Museum, London.






Wensleydale

Located near the village of Woodhall, between Aysgarth and Askrigg, the Wet Grooves Mine was worked on a series of veins for lead during the 18th and 19th centuries. According to Dunham & Wilson (1985), the dumps from these workings contained enough fluorspar to merit reworking during the time after the Second World War. In recent years the accessible portions of the mine have yielded some good specimens of colorless to yellow fluorite associated with barite and calcite to local collectors.


A 10 cm mound of pale yellow fluorite crystals with minor included sulphides. From the Wet Grooves Mine, near Woodhall, Wensleydale.


The Seata Mine is a small 19th century lead mine on the south side of the River Ure, just west of Aysgarth. The mine workings consist of several open-cuts and short adits within a quarry of the same name. Dunham & Wilson (1985) report the presence of flats containing fluorite and galena associated with veins at the mine, which have yielded specimens of amber and yellow fluorite to local collectors in recent years.


A tabular, amber-yellow fluorite crystal on a bed of smaller fluorites, from the Seata Mine, near Aysgarth, Wensleydale. 7 cm across. The crystal is twinned, which is unusual in this region.

The Raygill Level is located south of the River Ure between Bainbridge and Hawes. The level was worked for lead during the latter part of the 19th century, and has occasionally given up specimens of colorless, pale yellow and purple fluorite with associated barite and sulfides to visiting collectors. Dunham & Wilson (1985) report that recent inspections have shown the exposed section of the vein to be barren of ore, but report mineralized flats in association.






Wharfedale

The Gillheads Mine (also sometimes known as Troller’s Gill) is located near the village of Appletreewick, between Grassington and Pateley Bridge, accessing a vein of the same name along Skyreholme Beck. The mine was originally developed for lead during the 19th century, and is one of the few in the region that was reopened for fluorspar during the 20th century. The principal periods of activity were between 1920-1930 and again briefly around 1980. Fluorite specimens from the mine are typically colorless to pale yellow with a characteristic thin blue/purple layer at the surface.


A cluster of colorless fluorite crystals showing a pale blue layer at the surface. 8 cm across. From the Gillheads Mine (Troller's Gill), Skyreholme Beck, Wharfdale.


The Escoe House Level on Elbolton Hill (sometimes referred to as the "Elbolton Mine") is another small 19th century lead mine, located near the village of Thorpe, southeast of Grassington. The underground workings, while in poor condition, have on occasion yielded specimens of colorless fluorite with a deep indigo-blue surface layer in recent years. Another interesting feature in the area is a series of well-preserved medieval “bell pit” excavations that follow the trace of mineralized veins across pasture land just southwest of the village.


A plate of colorless fluorite crystals with an indigo-blue surface layer, from the Elbolton Hill, near Thorpe, Wharfdale. 15 cm across.





Nidderdale

A complex of veins near the village of Greenhow, west of Pateley Bridge were worked for lead during the 19th century, and some of the mine tailings contained enough fluorspar to merit reworking in more recent years (Dunham, 1952). The principal location in the area for specimens, however, has been the Coldstones Quarry, a modern open cast for crushed stone. The quarrying operation has cut two mineralized veins – the Coldstones Sun and the Garnet veins – and has occasionally breached old underground workings on these veins. Fluorite specimens recovered from the quarry are typically colorless to pale yellow, often with a thin blue or purple layer at the surface, not dissimilar to those found at the Gillheads Mine. Nearby is the smaller and now disused Duck Street Quarry, which also yielded fluorite specimens from exposed mineral veins.


A cluster of fluorite crystals with associated barite from the Coldstones Quarry, near Greenhow, Nidderdale. The fluorite is colorless with a thin lavender-purple layer at the crystal surface. 8 cm tall.