Important Specimen Producing Mines in and Around Weardale - Page 1



Introduction

Over the last several centuries numerous mines and prospects in the Weardale area have yielded enormous amounts of both lead and later, fluorite ores. As a byproduct of this mining, many well crystallized specimens of fluorite and other minerals were recovered, and are today found world-wide in both public and private collections. Fortunately for the mineral collecting community, there was a high level of interest in collecting and preserving mineral specimens in the UK during the late 19th and early 20th centuries, when many of these mines were at their peak production. This interest provided an economic incentive for miners to preserve attractive specimens, known locally as "Bonnie Bits", which they could readily sell to collectors and dealers. Coupled with this was a variable, but generally tolerant attitude on the part of the local mining companies toward collecting by the miners.


A cluster of well-formed, twinned fluorite crystals, 7 cm across, from the Boltsburn Mine.


But as they say, "all good things come to an end", and this is certainly the case with mining in Weardale. The collapse of lead prices in the late 19th century caused many local lead mines to cease production. The coincident rise in demand for fluorspar for use in modern steel-making gave a reprieve to many of the mines, but the collapse of the British steel industry in the early 1980's, followed by a glut of fluorspar from foreign sources has put an end to large scale commercial mining in Weardale, and throught the UK. The occasional specimen will still show up from collectors who visit quarries and the few underground mines still accessable, and attempts at commercial specimen recovery are happening at the Rogerley, Greenlaws, and St. Peter's Mines. Given the high cost of rehabilitating and running an underground mine, coupled with ever-increasing environmental concerns, it is likely that the "glory days" of specimen production in the area are past.

There is a body of literature on the history of mining in Northern England, and some excellant technical reports, but almost nothing documenting the tremendous production of world-class mineral specimens from this region. This page, which is hopefully a small step toward correcting the situation, is based on published accounts including Dunham (1990) and Fairbairn (1996), along with the author's admittedly limited personal observations. Additional information on any of these mines and their minerals, as well as correction of any errors in the following would be gratefully appreciated by the author.

A Note on Specimen Labels

Many older fluorite specimens from the Weardale area are labeled as coming from "Cumberland", "Alston", or "Alston Moor". Cumberland is an antiquated name for a county that was combined with Westmorland in the 1970's to create the modern county of Cumbria. Weardale is, and always has been in County Durham to the east of Cumbria, and thus to label Weardale specimens as being from Cumberland is incorrect. The confusion most likely arose during the late 19th and early 20th centurys when most local mineral dealers were operating in the town of Alston, which was in Cumberland - now modern Cumbria. Specimens from the Weardale mines were bought from the miners by the Alston-based dealers, who then provided only generalized location information, either through neglect or in an effort to protect their sources.


A specimen of fluorite with siderite, almost certainly from the Boltsburn Mine in Weardale, with a label giving the location as "Alston Moor."

This is not to say that all fluorite specimens from the region came from Weardale. The Hilton Mine in Westmorland (now Cumbria) is famous for its amber and yellow fluorite. Good fluorite specimens have also come from the Beaumont (Allenheads) and St. Peters Mines in Northumberland. These, however, are distinctive and not likely to be confused with specimens from the Weardale mines. The Rotherhope Fell Mine, located in Alston Moor is likely to be the one source of confusion. During the first half of the 20th century this mine produced some very good specimens of purple and amber-yellow fluorite, which are very similar in appearance to those from any of a number of Weardale mines. Without proper documentation these specimens may be difficult to distinguish from specimens that came from the Boltsburn Mine and other mines in Weardale.



A map of the Alston Block area of the North Pennines showing important specimen-producing mines and other geographical features. Map by Peter Briscoe.




Allenheads (Beaumont) Mine


The Allenheads Mine was historically the most productive mine in Allendale and worked a series of interconnected veins at the head of the East Allen River Valley. The earliest workings in the area probably date to the 16th century and were located to the west of the village of Allenheads. During the 18th and 19th centuries the mine was operated by the Beaumont Company who produced an estimated 260,000 tons of lead concentrates (Dunham, 1990). Early work focused on the Old Vein, which was largely mined out by the begining of the 19th century. Toward the end of the 18th century the Diana Vein was discovered at the western end of the Old Vein and yielded ore from a productive section of flats. In 1822 a cross-cut driven south from the Diana Vein encountered the Coronation Vein, which contained extensive flats spanning both the Middle and High Flats horizon of the Great Limestone. These deposits were worked until 1840.


A cluster of pale lavender twinned fluorite crystals, sphalerite and ankerite, 10 cm across, from the Diana Vein. Recovered ca. 1970.


Mining began on Henry's Vein in 1825, and during the latter part of the 19th century accounted for the majority of the ore production from the mine. The vein was accessed by an underground shaft and a over 2.5 km of vien was worked, largely in the Great Limestone. The mine was closed by the Beaumonts in 1896 due to depressed lead prices on the world market. With the rise in demand for fluorspar, the dumps were reworked in the 1940's. In 1969 British Steel Corporation reopened the mine (calling it the Beaumont Mine) hoping to find fluorite that had been left behind - either in place or as backfill by previous lead mining operations. Several new declines and levels were driven to access both the Diana and Henry's Veins, but the hoped for quantities of fluorspar were never found. Specimens were recovered from both veins during this period, and of particular interest are those from what remained of the flats surrounding the Diana Vein. The mine was closed in 1981 and is now completely flooded.


A cluster of purple, untwinned fluorite crystals with associated siderite and galena from Henry's Vein. Recovered during the 1970's.



Blackdene Mine

The Blackdene Mine is located just north of the River Wear, between the villages of St. John's Chapel and Ireshopeburn. Lead mining on many of numerous veins in this area dates back to at least the early 15th century. The Blackdene Mine proper was originally developed by the Beaumont Company in the early 19th century for lead. The main workings follow the Blackdene Vein northeastward from near the banks of the River Wear, and eventually intersected those of the Elmsford Mine which worked a nearby section of the Slitt Vein.


A deep purple twinned fluorite crystal, 2.2 cm on edge, on a cluster of smaller opaque fluorites. From the workings on the Blackdene Vein ca. 1965.


Fluorspar was mined from both the Blackdene and Slitt Veins during the early 20th century, but the mine appears to have been abandoned when acquired by United Steel in 1949. Extensive exploration and development in the Blackdene occurred during the 1950's at levels between the Three Yard Limestone to below the Scar Limestone. By 1973 commercial reserves on the Blackdene Vein appeared exhausted, and a new incline was driven to access unmined portions of the Slitt Vein. With nationalization of the steel industry, ownership of the mine passed to British Steel, but it was disposed of when the industry crashed in 1982. Weardale Mining and Processing continued to operate the mine until 1987 when it was finally closed. Most of the mine is now inaccessable due to flooding.


A cluster of twinned purple fluorite crystals with a sharp 2 cm cube-octahedral galena crystal. From workings on the Slitt Vein ca. 1973.

The Blackdene Mine is best known for its production of medium to dark purple fluorite crystals, associated with lustrous galena crystals of complex habit and other sulphides on white quartz matrix. Smaller fluorite crystals (up to 5 cm) are frequently lustrous and transparent, while larger ones are usually opaque. These larger crystals are often elongate, giving them a tetragonal rather than cubic appearance. Fluorite crystals in varying shades of yellow and green have also been found in the mine, and the rarest are combinations of the two. Well formed calcite in a variety of forms was found as well. The best specimens from the mine appear to have come from the recent workings on the Slitt Vein.


A twinned yellow fluorite crystal, 2.5 cm across with a faint green core, on a quartz matrix. From the Blackdene Mine, Slitt Vein.





Boltsburn Mine

The main shaft of the Boltsburn Mine is located on the west side of the village of Rookhope near the intersection of the Boltsburn and Red Veins, and the workings of the Boltsburn Mine proper follow the Boltsburn Vein to the northeast. The mine was originally developed for lead ore in the early 19th century by the Beaumont Company, but with only modest success. It was later taken over by the Weardale Lead Company, who, in 1892 discovered the increadibly mineralized flats this mine is famous for. Mining of the flats, located at the High Flat horizon in the Great Limestone continued northward, and eventually reached a point more than 3 km from the main shaft. As the strata dips gently to the north, this ment the workings became ever deeper with distance from the main shaft, thus a succession of new shafts and levels had to be driven as mining progressed. Despite the presence of ore at the face, the mine closed in 1932 because of labor problems and the high cost of transporting ore out of the mine.


A well-formed twinned, purple fluorite crystal, 5.5 cm on edge, with minor siderite, from the Boltsburn Mine.

The flats encountered in the Boltsburn Mine were, without a doubt, the best example of this type of mineralization found in any of the mines around Weardale. Besides yielding large amounts of galena, cavities in the flats contained numerous large, well developed fluorite crystals. Many of these were of optical quality, and exceeded 20 cm in size. Due to their perfection, many were purchased by German companies such as Zeiss for use in precision optics for microscopes. Fortunately, many were also preserved and now grace museum and private collections.

The following description of these deposits is excerpted from "The Boltsburn Flats - Their Interest to the Student of Nature" by Stephen Watson, a mine agent for the Weardale Lead Company, which was published in 1904 in the Weardale Naturalists' Field Club Transactions. It is one of the few contemporary descriptions of such deposits ever published:

"The flats under notice in this paper are those in connection with Boltsburn vein, which are now being worked eastward from the watershed of Rookhope and Stanhope burns at a depth of over 100 fathoms below the surface, the mining excavations on which have revealed phenomena of interest to the geologist, the mineralogist, and the general student of nature....Instead of the usual well defined three flats we find one large flat, and as a consequence the loughs or cavities are on a larger scale than ordinary, in some cases forming caverns of considerable magnitude. These spaceous chambers give Nature the opportunity of modelling her creations on larger lines hence the massive cubes of fluor spar and huge bosses of crystallized galena. Entering one of these caverns immediately after being broken into by the miners, you find yourself surrounded by crystallized fluorite, the only stepping places being points and angles of six inch cubes. You admire the various shades of purple blue and heliotrope in the translucent crystals, and notice that some of the others are pale and cloudy. As you move carefully along its winding course, new forms of groups arrest the eye, and you note that some of the cubes are studded with calcite, and others are coated with fine white quartz, the diamond-like sparkle of the latter showing very effectively against the dark background of fluor. Another bend any you are confronted with an isolated cube measuring 12 inches across its face, and perfect in every line and angle. Having walked some 20 or 30 feet you find your further progress barred, although the vista of beauty still extends as far as the light of your candle can penetrate. Another type of lough is low and wide-spreading, paved with fluorite and roofed with pure galena 6 to 12 inches thick in some cases, chemical affinity thus showing itself curiously antigonistic to the force of gravitation; more commonly however these minerals are found irregularly distributed over floor and roof alike. Chalybite or iron carbonate sometimes predominates in a lough, every part of which is then rounded off and combed over with a moss-like formation, light brown, pale yellow, or whitish in colour, with a few minute crystals of fluorite scattered here and there upon its surface. Some of the smaller loughs are the most showy, the fluorite displaying a finer finish, the galena a more silvery lustre."


A transparent, twinned, pale lilac-pink fluorite crystal, 2.2 cm on edge, with numerous smaller fluorites, from the Boltsburn Mine.


The Boltsburn Mine is best known for its large, gemmy, twinned fluorite crystals. The most common colors were shades of lavender to medium purple, but most colors except green were found. Color banding in Boltsburn fluorite is usually not pronounced. Overgrowths of fine grained, bronze colored siderite are often present on selected faces of the fluorite crystals. Other associations include lustrous galena crystals of cubeoctahedral to complex habit, calcite, and white druzy quartz. Other sulphides found in lesser amounts included sphalerite and pyrite. Exploratory drilling in the 1970's showed that the flats continue at least 150 meters beyond the point where mining ceased. Despite this, it is unlikely the mine will ever reopen due to the high cost of rehabilitating the original workings or driving new tunnel to reach the flats.


A cluster of well formed cube-octahedral galena crystals up to 2 cm across, with associated siderite. From the Boltsburn Mine ca. 1920.



Brownley Hill Mine, Nenthead, Alston Moor, Cumbria

The Brownley Hill Mine (sometimes called Bromley Hill) is located approximately 1 km northwest of the village of Nenthead, Alston Moor, Cumbria. The mine accesses a number of associated veins and flats, with workings developed primarily in the Great Limestone. The earliest records indicate that work at the Brownley Hill Mine dates back to at least the first half of the 18th century. During the latter 18th and most of the 19th centuries the mine was worked for lead by a succession of independent lease-holders and small mining companies. By the latter 19th century high grade lead ores had become depleted and production shifted to zinc. The final leasee was the Vieille Montagne Zinc Company of Belgium, who operated the mine until 1936.


Alstonite (crystals up to 6 mm) on barite from the Brownley Hill Mine, Alston Moor.


The Brownley Hill Mine is located at the outer boundary of the Weardale fluorite zone, and though somewhat rare, specimens of amber fluorite have been recovered from mine workings on the Jug Vein. The mine is perhaps best known as being the type locality for alstonite - a relatively rare barium-calcium carbonate. First described as a variety of barytocalcite in 1835, the mineral was correctly recognized as a new species in 1841. The exact location of the original alstonite occurrence was not recorded, but was rediscovered in the late 1980's by Lindsay Greenbank. Alstonite has also been found at the Fallowfield Mine in Northumberland, but can be distinguished due to its association with witherite, where-as that from Brownley Hill is often associated with calcite and/or pink to tan barite.


A cluster of untwinned amber fluorite crystals up to 3 cm on edge, with minor chalcopyrite, from the Jug Vein, Brownley Hill Mine.




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