MINERALS & SPECIMENS

After many centuries of mining, initially for lead and iron-ore and in later years, fluorspar, the last commercially worked mine, Frazer’s Hush, closed in 1999
The only present-day activity are specimen operations at St.Peters, Rogerley and Greenlaws plus two large-scale quarrying operations which periodically hit mineralised ground.
The best specimens are found in flat workings extending laterally from the host vein.The most prolific host strata for specimens is known as the Great Limestone with a thickness of up to 22 metres. Throughout the orefield three distinct horizons in the Great Limestone are prone to flat mineralisation often with large crystallised cavities.
At Boltsburn mine flats extending for some 7,700 ft along the vein and up to 200 ft from it, producing some of the finest fluorspar specimens in the world. More recently, in the late 1980’s, on the 325 level at Cambokeels level a zinc-rich flat was discovered. After starting mining, the drillers complained to the management that they couldn’t work the area because the drill rods kept disappearing into cavities!
The ore-field is zoned laterally with the central area primarily fluorite and the outer fringes containing barite. Crystallised galena, calcite, siderite, quartz and pyrite also occur with amounts of sphalerite increasing towards the west of the ore-field.
Specimens from classic Weardale locations are becoming increasingly difficult to find due to the end of commercial mining.

Beaumont Mine, Allenheads, Allendale, Northumberland.
Known for its specimens of lustrous wine coloured fluorite partially covered with sphalerite and siderite found in the early 70’s from Diana vein. These were a pale green colour when first brought out. Opaque purple fluorite cubes from Henry’s vein. Closed 1979.

Blackdene Mine, St. Johns Chapel, Weardale.
Transparent purple fluorite cubes to about 5cms and rarely highly prized green/yellow and exceptionally Green/purple/yellow cubes found in a cavity when driving the incline. Larger cubes up to 15 cms, but of a opaque purple and white colour. Elongated purple ‘floater’ crystals. Modified bright galena crystals, the best found at the bottom end of the incline. Chalcopyrite and pyrite crystals on fluorite. Calcite in many forms sometimes with curved crystal faces and coating fluorite. Large sphalerite balls to the size of footballs. Closed 1987 with all the recent workings off the incline flooded.

Boltsburn Mine, Rookhope.
Most colours of fluorite (except green) with some of the largest and finest cubes ever found. Many other aesthetic specimens with fluorite cubes partially coated with siderite, galena, sphalerite, pyrite and occasionally chalcopyrite. Unusual calcite crystal stalagmites. Closed 1932.

Cambokeels Mine, Westgate, Weardale.
Upper levels produced large crystals of pastel coloured fluorite. Lower levels produced some of the finest pyrrhotite crystals in Britain; the 325 level ‘zinc flat’ yielded many excellent specimens of clear to turquoise fluorite crystals with colour-zoning, sometimes aesthetically sprinkled with pyrite or coated with small sparkling quartz crystals or calcite. Although rich in zinc only small crystals of sphalerite were found in the flat and galena seems to be absent. On the 340, the lowest level, unusual pink transparent twinned fluorite cubes on quartz were found. All levels at Cambokeels produced fine specimens of calcite in many different habits. Zeolite specimens are also recorded. The mine closed in 1989 and all the lower levels off the incline are now flooded.

Groverake Mine, Rookhope.
Banded chalcedony often coating fluorite. Quartz crystal beds were common. Worked for most of the 19th Century until 1985 then re-opened and closed in 1999.

Heights Quarry and Mine, Eastgate, Weardale.
Occasional producer of the finest quality specimens of lustrous green fluorite with inter-penetrant cubes to 4cms. Also purple and colourless material some with included 'bubbles'. Various combinations of fluorite, galena, calcite and aragonite. Very large green opaque fluorite crystals up to10cms from West Cross vein.

Redburn Mine, Rookhope
Beds of small purple fluorite. Also produced some excellent specimens of ‘Jack-straw’ cerussite. Closed 1981.

Rogerley Mine, Frosterley, Weardale.
Small mine driven in face of quarry, initially developed by Lindsey Greenbank and Mick Sutcliffe; currently by UK Mining Ventures for specimens. Occasionally excellent green specimens and recently large purple fluorite cubes with quartz. Flos-ferri aragonite.

Stotfield Burn Mine, Rookhope.
Lustrous, transparent grey-green and grey-purple fluorites. Modified galena cubes to 3 cms. Closed 1966.

West Pasture Mine, Stanhope, Weardale.
Beautiful apple-green fluorite cubes have been collected in recent years. The colour is particularly unstable in sunlight and alters to a pale purple-brown. Also larger purple fluorite crystals.

Whiteheaps Mine, Hunstanworth, Northumberland.
Light pastel coloured groups of fluorite with crystals up to 4cms.and occasionally of a deeper purple colour. Sphalerite and calcite specimens but rarely galena. Closed 1980.