Minerals of the Alston Moor orefield

Alston Moor is a name synonymous with superb galena, sphalerite, fluorite, witherite, and of course - Alstonite. Collections the world over have specimens from the area, unfortunately all too often labelled simply 'Alston Moor'. The area covers some 25 square miles - with some of the accessible workings still reaching more than 2 miles into the depths of the Pennines. A network of huge faults introduced mineralising fluids to the interbedded limestones and shales of the area - creating huge flats where the fluids invaded susceptible limestones and dissolved them, leaving behind crystal filled cavities sometimes big enough to walk around in.

Many photos here are self collected pieces - lower down the pages are a selection I recently acquired from the Philadelphia Academy of Natural Sciences collection in the USA. They are much older, and would have been mined in the mid 1800's - thus represent a different time slice of the mineralogy as it was mined.

Personal Experiences

I almost started my collecting career in the area. Some of the first mines I ever went down were Smallclough, Rampgill, and Brownley Hill. In the 1970's, collectors had barely touched the underground workings, and crystal filled cavities were to be found everywhere. We would go underground for days at a time, gazing in awe at the vastness of the flats, the almost never ending twisting, turning tunnels which drove ever deeper into the hills. Artefacts lay everywhere - old tubs, mining tools, timber, explosive boxes, water bottles - but over the years they've largely disappeared, the cavities raked clean, and the workings are starting to deteriorate as the long drives through the softer shales slowly deteriorate. There are many dedicated conservationists and mine-explorers, but too few to save these mines from collapse in the long term I fear. Nentsberry Haggs was the first to go - massive collapses in the horse level make it all but inaccessible these days. Gudhamgill has been lost for years.

The first place we ever found was called Hydraulic Shaft. I don't know how we found it - I think Dick Barstow had heard about a spot where sphalerite might be collected - so we went for a look. After a fruitless couple of hours we found some cast iron pipes leading down a tunnel to the top of a shaft. Was this it? Sphalerite crystals glittered everywhere on the walls - little cavities abounded. They seemed bigger on the other side so we found some iron rails and laid them over the shaft to get across - and immediately found the entrance to what became a massive hole - friable limestone which was almost completely dissolved and brecciated, cemented with sphalerite. In those days nobody had ever seen the stuff - everyone wanted a piece, and we collected dozens of specimens every time we went in - including slabs up to 3 feet across, covered in crystals up to 2cm across. There's actually two cavities now - with different styles of mineralisation. The second is fascinating, because there are solid sheets of sphalerite in the base of the cavity displaying ripple marking - clear evidence of the nature of ore formation - zinc rich fluids running through the limestones depositing their metals as they went.

On the way through the flats, names like 'Incline Flats' and 'Wheel Flats' crop up. There's galena and dolomite everywhere in those flats. You used to be able to gaze into almost bottomless holes, marvelling at the beauty of the shiny galenas that lined them. Idiots with nothing better to do than rake down the sides of the cavities with long chisels soon finished that - but in some areas - towards the edges of the flats, there are spots where a good dig in the floor reveals new cavities that are collectable. These are some of the nice ones I've collected over the years - nothing like the monsters in the Natural History museum, but good, nevertheless.