Alston Moor
The barium capital of the North Pennines: witherite, barytocalcite and alstonite, alongside the fluorite, galena and sphalerite that paid for the mines.
Alston Moor in Cumbria is the barium centre of the North Pennine orefield. Alstonite, barytocalcite and witherite all take their collector reputation from Alston Moor mines, alongside fluorite, galena and sphalerite. The London Lead Company worked the ground from 1704; the Belgian Vieille Montagne company held the Nenthead leases from 1896 until 1949.
In short
- Alston Moor is the western block of the North Pennine orefield, around the town of Alston (postcode district CA9) and the mining village of Nenthead, in Cumbria.
- Barytocalcite was described from Blagill Mine here in 1824. Alstonite, its triclinic dimorph, came from Brownley Hill in the 1830s and is named for the district.
- Witherite, barium carbonate, was recognised as a distinct mineral in 1784 by William Withering, from lead-mine samples off Alston Moor.
- The classic specimen mines are Smallcleugh, Rampgill, Brownley Hill and Nentsberry Haggs, in and around Nenthead.
- Also fluorite, galena, sphalerite, barite and calcite, plus millerite and a suite of rare supergene species from Brownley Hill.
| Species | Formula | System | Hardness |
|---|---|---|---|
| Witherite | BaCO3 | Orthorhombic, pseudo-hexagonal twins | 3–3.5 |
| Barytocalcite | BaCa(CO3)2 | Monoclinic | 4 |
| Alstonite | BaCa(CO3)2 | Triclinic, pseudo-hexagonal | 4–4.5 |
| Barite | BaSO4 | Orthorhombic | 3–3.5 |
| Calcite | CaCO3 | Trigonal | 3 |
| Fluorite | CaF2 | Cubic | 4 |
| Sphalerite | ZnS | Cubic | 3.5–4 |
| Galena | PbS | Cubic | 2.5 |
Why Alston Moor is a barium district
The North Pennine orefield is mineralogically zoned, and that zoning is the single most useful thing a collector can know about it. Mineralising fluids rose around the buried granite under the Alston Block, and what crystallised depended on how far from that heat source the fluid had travelled. Close in, you get the fluorite zone — which is why Weardale and the Rogerley are fluorite country. Further out, on the margins, barium minerals take over.
Alston Moor straddles that transition. It has fluorite, and good fluorite, but its distinctive contribution is barium: barite in quantity, and three barium carbonates that between them made the district's name in mineralogy. Two of the three were described from here.
The ore that paid for all of it was galena, worked for lead and for the silver in it, later followed by sphalerite worked for zinc. The barium and calcium carbonates were gangue — the worthless stuff the miners cut through and threw out. That inversion, where the discard becomes the collectable and the ore becomes the ordinary, is the whole story of British mineral collecting in miniature.
Witherite, barytocalcite and alstonite
Witherite is barium carbonate, BaCO3. William Withering, the Birmingham physician better known for digitalis, examined samples from an old lead mine on Alston Moor in 1784 and established that the mineral was chemically distinct from barytes. It was later named for him. It typically forms squat pseudo-hexagonal twinned crystals and rounded, ribbed masses, white to pale yellow, and Nentsberry Haggs produced exceptional material.
Barytocalcite is BaCa(CO3)2, monoclinic, first described in 1824 from Blagill Mine on Alston Moor — its type locality, and for a time a commercial source of the mineral. It occurs as slender prismatic crystals and cleavable masses, transparent to translucent, white through yellow to grey.
Alstonite has the same formula as barytocalcite but a different structure: triclinic, with complex twinning that makes crystals look pseudo-hexagonal. It was found at Brownley Hill in the 1830s and named for Alston Moor, with Fallowfield Mine in Northumberland as the second co-type locality. Habit is the usual first clue — sharp, steep, pointed pseudo-hexagonal pyramids, often colourless to pale pink.
Telling alstonite from barytocalcite by eye is genuinely hard, because the composition is identical and only the structure differs. Habit and optics will usually get you there; a specimen that matters should have a determination behind the label rather than a guess.
Nenthead: Smallcleugh, Rampgill, Brownley Hill, Nentsberry Haggs
Nenthead, high on the moor southeast of Alston, is where most of the collectable material came from. Smallcleugh and Rampgill are the big London Lead Company workings, extensive enough that their levels have been a focus for mine explorers for decades, and both produced fluorite, galena, sphalerite and calcite.
Brownley Hill, about 4 km east of Alston, is the specimen mine of the district and one of the few major workings in the Nenthead area not developed by the London Lead Company. It is the source of the alstonite that carries the district's name, and it also produced fine galena, fluorite, sphalerite and millerite, along with a suite of rare supergene species — brianyoungite and bottinoite among them — that give it a standing out of all proportion to its size.
Nentsberry Haggs lies immediately northwest of Brownley Hill and connects to it underground. It produced exceptionally fine barytocalcite and witherite, and cabinet-sized alstonite, barite, galena and sphalerite. If a British witherite stops you in a case, there is a fair chance it is from here.
1704 to 1949: the London Lead Company and Vieille Montagne
Lead has been taken off Alston Moor since medieval times, but the modern district begins with the London Lead Company — the Quaker Company — which acquired its charter in 1704 and took over the Ryton Company's Alston Moor mines the following year. It ran most of the mining and smelting on the moor for the best part of two centuries, built much of Nenthead as a company village, and reached peak production in the 1820s.
Decline followed, and the collapse in lead prices in the early 1880s ended it: the company gave up its last Nenthead leases in 1882. The Nenthead and Tynedale Zinc Company took them on, and in 1896 the Belgian Société des Mines et Fonderies de Zinc de la Vieille Montagne arrived at Nenthead, reworking both the mines and the old lead-era waste dumps for zinc. At one point Vieille Montagne accounted for around 60 per cent of United Kingdom zinc output. After fifty-three years it sold its leases, plant and equipment and left in 1949.
This matters to a collector because it dates material. Specimens from the London Lead Company era carry old handwriting and old collection numbers; the Vieille Montagne period reworked ground that had already been picked over once; and almost everything that reached the market after 1949 came out through mine exploration by collectors rather than through commercial mining.
Buying Alston Moor material, and going there
Most good Alston Moor specimens are old. That makes labels central, and it makes provenance chains worth reading carefully — British locality labels of the mid-twentieth century are not uniformly reliable, and the collecting world has had to re-examine more than one celebrated British suite where the localities did not survive scrutiny. Where a piece has a continuous chain back to a named collection, that is worth paying for. Where it has a single unsourced card, treat the locality as an attribution rather than a fact.
What to look for: witherite in ribbed pseudo-hexagonal twins with a good waxy lustre; barytocalcite in sharp prisms rather than cleavage fragments; alstonite in steep colourless to pink pyramids with the terminations intact; and Nenthead fluorite, which runs green, purple and colourless and is less celebrated than Weardale's only because Weardale's is extraordinary.
On visiting: the surface remains at Nenthead are of national importance and much of the complex is a scheduled monument, which means it is protected by law and is not somewhere to dig. Access arrangements to the site and to the underground workings have changed repeatedly over the years and are not ours to state. Check the current position with the landowner or site operator before travelling, and do not go underground in old lead workings without the people and equipment for it.