Lead ore (Galena)
What is a galena?
Galena is lead sulphide (PbS). It is the most important ore of lead (and often also silver). It was mined extensively in the northern Pennines and especially around Allenheads.
How do I recognize it?
It is a silvery coloured mineral that often looks like interlocking cubes. It is quite soft and will mark “write on” other stones.
Where do I find it?
The best places in Northumberland are spoil heaps adjacent to old mine sites, but you can sometimes find it occurring in veins in rocks. It is often associated with zinc ore (sphalerite), fluorite, quartz and calcite.
How was it made?
It was formed when hot mineral-rich fluids percolated through the rocks and then cooled and crystallised.
What does a lead mine landscape look like?
A 100 years ago and more they would have looked like an industrial wasteland. They are slowly returning to nature but you will still see the buildings, scars and spoil heaps resulting from lead mining in the areas around Allenheads.
Which plants like galena?
The heavy metals associated with galena – like cadmium – are very toxic and travel downstream in rivers; only a few plants will tolerate growing on soils contaminated with them. They produce a very rare habitat – like the one at the NWT reserve at Beltingham – it is called calaminarian grassland.
What use is it?
Lead is used in roofing, car batteries, ammunition and previously for paint and pipe manufacture.