The town of Oswestry is situated upon and near the southern termination of the North Wales Coal Field, which extends a little farther south of the town, and, north-west, through Ruabon, Brymbo, Flint, Mostyn, and on to the sea, near the Great Ormshead. Running parallel, and lying at the back, or to the west of these coal-measures, is the great belt of mountain limestone, commencing at Llanymynech Hill, and extending also, north-westerly, to the Ormshead, and from thence dipping into the sea.
The metalliferous character of the district is distinguished for the production of lead, copper, and zinc. Trials have been made for minerals at Treflach Wood, and portions of carbonate and sulphuret of copper, of average qualities, have been found, but not in sufficient quantities to justify extended operations. At Llanymynech Hill both copper and lead, sulphurets and carbonates, with carbonate of zinc, or calamine, have been raised in large quantities by various companies, and occasionally the ores have reached a high per centage, ranging from five to twenty-five per cent. The ores are found in beds or flats, at from thirty to fifty yards from the surface, and lying between, and running parallel with, the strata of limestone that inclose them. It is an extraordinary fact, that the metalliferous belt of limestone abruptly terminates at the south end of the hill, and cannot be traced farther. Proceeding west, at the back of Oswestry, in Treflach Wood, there are some fine beds of Derbyshire marble or entrochal limestone, that have been worked for mantle-pieces and other ornamental purposes.
Trials have been made, and small quantities of lead and copper found in this limestone belt, extending to Minera, including the Eglwyseg range which bounds a portion of the Vale of Llangollen, near to Ruabon.
The Minera district is too well known for its rich mineral products, especially of lead and zinc, to require particular notice, and the same may be said of the Mold, Halkin, and Holywell mineral formation, passing on with continued fine mineral deposits, to Talargoch, near Prestatyn, in Flintshire.
The coal-measures in the district of Oswestry abound in fossils, Lepidodendrons, Sigillaria, Stigmaria, and Calamites, &c.; and the carboniferous limestone is much more prolific of that class of fossiliferous productions which usually accompany the old mountain limestone.
The application of capital and scientific labour to mining operations, during the last ten years, has given to the district an active and business-like character, and brought with it a large increase to the working population. At Llanymynech Hill, in addition to mining operations, there are annually raised about 60,000 tons of limestone, which is chiefly used for farming purposes in Montgomeryshire and Shropshire. At Porth-y-Waen rocks, in the same range, there is nearly the same quantity of limestone raised. The united quantities hewn and blasted from these vast limestone rocks produce about 70,000 tons of burnt lime, thus showing the extended use now made of limestone in the cultivation of farm lands in the immediate district.
The manufacture of iron is most extensively carried on in Ruabon parish, principally by the New British Iron Company, the quantity of good bar iron made amounting on the average to 350 tons per week. These works give employment to about 2,500 people, men and boys. The Company works its own collieries, and consumes nearly all the coal its numerous pits produce. In the same parish there are two extensive manufactories, for the conversion of the ores of calamine and black jack (carbonate and sulphuret of zinc) into zinc or spelter, and at each of these places from twenty to thirty tons of these metals are made.
The coals raised from the coal-fields in and around Oswestry, worked by Messrs. Croxon and others, amount to about 40,000 tons per annum; whilst nearly 250,000 tons are raised in the Ruabon district, and a much larger quantity at Brymbo.
At Minera a powerful Company is actively engaged in working the old mines that produced so much ore during the former operations upon them. These mines were closed from the influx of water, and the inadequacy of the machinery then employed to carry it off. The present Company have, with an enterprising spirit, adopted the highest class of machinery, and employed the best mining talent that could be procured. By these means, which have called forth the application of at least £50,000 to this gigantic undertaking, the Company has fortunately succeeded in discovering rich veins of lead-ore, which produce from 100 to 150 tons per month. Other mining companies are also largely engaged in the district, some of which are producing large quantities of lead-ore.