Within the structure of the rocks underlying the UK are many useful materials including ores, gemstones, coal and oil. Detecting them is a different matter. Once, it was a hit or miss process relying on keen eyes or methodical prospecting. As the science of geology accumulated knowledge, the process of hunting for earth's riches became more targeted as the reasons why some minerals were found at particular sites were determined. Today, the structure and mineral wealth of Scotland is increasingly understood.
Underground - the minerals
Where conditions were suitable organic remains have been mineralised. Prehistoric forests built up vast deposits of timber and leaf mould. Just as with any other sediment, time, heat and pressure caused changes. The solid carbon rich matter remains as coal but heat and time drive of much of the other hydrocarbons present in the original deposit. Volatile organic compounds are found in special circumstances as oil and natural gas. These only persist underground where an impermeable rock layer prevents them percolating to the surface (where they are mixed in the environment and rejoin the organic cycle).
As well as coal the central valley of Scotland has rich deposits of oil-shale, a fine grained sediment with a substantial organic component. The latter can be driven off as crude oil by heating the shale. In the Nineteenth century the oil-shales supplied much of British industry with fuel and a wide range of chemicals.
Iron can be extracted from a wide variety of ores, which in the UK range from the curious, kidney-shaped oxide haematite to massy black-band ironstones. The ores were worked extensively throughout the industrial revolution, which eventually demanded millions of tons of iron every year. With rich ores, good coal reserves and abundant limestone, the central belt of Scotland developed as a major iron making region.
Limestones are sedimentary rocks comprised mainly of calcium carbonate. Deposits are used as building stone, as flux in iron making and were a source of lime for mortar and dressing agricultural land to reduce acidity. A large deposit of limestone and shale near Dunbar in East Lothian supplies much of Scotland with cement.
Deposits of sandstone and limestone have been worked in the UK for centuries as building material. Such are the qualities and availability of this material that stone was preferred and was cheaper than brick until late into the Nineteenth century. Differences in colour and texture of the local stone have given many localities a characteristic look.
In many places clay deposits began to be exploited on a large scale for pottery and industrial ceramics, like foiled drainage tiles, in the Eighteenth century. In the Nineteenth century fireclay began to be worked as an adjunct to coal mining. Kiln developments and mechanisation made bricks increasing competitive and the developing infrastructure of the railways and of the cities and larger towns began to use increasing amounts. As well as construction materials clay was used in the manufacture of kiln linings and domestic wares like sinks and chimney pots.
Minerals of economic importance are often found in veins. Veins are infilled channels in massy rocks, pathways where deep underground hot concentrated solutions selectively deposited crystalline materials. These spectacular crystals of galena and lead sulfide, occur in veins through the rocks around Wanlockhead and Leadhills. Mines in the past followed the twists and turns of the veins and lead was produced in the area until the 1950s. Wanlockhead is the type locality for around 10 different minerals - a reflection of both the richness of the deposits and Scotland's place in the development of geology.
Several regions of the UK have produced significant amounts of gold in the past and still provide pickings for dedicated gold panners. The gold occurs as traces in quartz veins but is best found in the gravels and silts that in the burns cross the regions. They act to concentrate the grains of weathered out gold.
As well as gold there are reserves of more prosaic minerals. Deposits of barytes, a dense and heavy rock rich in barium sulfate, are found in many places in the UK. The powdered rock is much in demand as a lubricant by the oil drilling industry (accounting for 88% of world output) and some is used in glass and ceramic production. A mine at Foss in Perthshire began to produce around 50,000 tons of barytes annually in the mid-1980s, supplying around ΒΌ of Scotland's offshore oil industry's needs.
Many of the resources on RLS were contributed by the Museum of Lead Mining, which is based in the heart of a rich mineral field that produced lead, silver and gold over the centuries. The museum began in a cottage at Wanlockhead in 1974 and has helped maintain the profile of Scotland's highest village since - not least when it hosts gold-panning championships - the British and Scottish annually and the World Championship occasionally.
The 'Scottish Mining Museum Trust' operates Lady Victoria Colliery near Edinburgh as a showcase for Scotland's vanishing coal mining industry. The Lady Victoria was one of Scotland's most innovative pits when it opened in the 1890s and it produced over 40 million tons of coal before it closed.
