Except in north-west Peeblesshire, no rocks of economic value occur in the two counties; unless greywacke (whinstone), useful for building and for road-making, may be so regarded. Before the period of tree-planting, whinstone was much in evidence as stone-wall fences. The whinstone being a stratified rock splits readily with a clean fracture. It has undergone many contortions, which render it difficult to deal with for building purposes, but the stonemasons of the district are famous for their skill in its manipulation, producing as they do with only a hammer and trowel beautifully-faced walls. Freestone abounds in the carboniferous tracts, white and yellow as at Carlops, chocolate-coloured as at West Linton. In the Dod Wood at Kirkurd are numerous old and new quarries of white and red sandstone, where the red stone of the buildings at Lyne Camp were probably obtained. Previous to 1841, before the geological record was thoroughly understood, the carbonaceous shales of coal and limestone were wrought at Carlops; and not so long ago a coal pit was worked at Macbie Hill, where still a little mining is done. Attempts were also made to find coal at Lindean and Galashiels; and anthracite was said to have been got at Grieston and Caddonfoot. But these attempts were bound to fail, because the sandstones, the limestone, and the millstone grit of the West Linton district all lie beneath the coal measures, which are naturally thickest in the middle of their hollow basin, and thinnest at the upturned edges. Such coal as is found in the district will be "edge coal" while "anthracite" found in Silurian strata is either black shale or has been formed from quantities of embedded animal matter.

Lead used to be worked on the Medwyn in the sixteenth century, and the excavations are now called "Silver Holes" from the fact that silver was once obtained there. In the seventeenth century a lead mine was said to exist on the north side of Selkirk, at the head of the Linglie Burn, and a silver mine at Windy Neil. Lead has also been mined for at the Bold Burn, at Grieston, at Windlestrae, at Kershope in Yarrow, and at Innerleithen, where smelting furnaces were discovered four feet beneath the surface in the churchyard. Gold is said to have been found in Henderland, in Glengaber, and Mount Benger Burns, in the reign of James V. A specimen from Glengaber Burn is preserved in the Peebles Museum. Gold is also recorded as having been obtained in the Douglas Braes at Douglas Craig and in Linglie Burn. The Regent Morton had a contract for working gold at Henderland. But the enterprise was unsuccessful. Veins of haematite occur here and there in Silurian rock. At Noble House a bed of red haematite shale lies among the green shales of the district, and was worked some twenty years ago. Iron pyrites occur at Bowerhope, and oxide of iron is found in many of the mosses. Silurian shales have often been worked for slate, as at Stobo and Grieston quarries. Out of the former many of the houses in old Edinburgh are said to have been roofed. These quarries are no longer worked, either because they are exhausted, or because better material is now more easily obtained. The felsite near Innerleithen has been used for making curling stones. Lime quarries are common in the West Linton district; and lochs in Selkirk have sometimes been drained for their marl, a mixture of lime and clay, invaluable to the farmer.

Mineral springs are fairly numerous. A century ago the well-known chalybeate spring at Innerleithen made the village a fashionable summer-resort and furnished Sir Walter Scott with a setting for his romance, St Ronan’s Well. This spring used to be known as the "Doo Well" because of the pigeons that flocked to it. A sulphurous spring at Castlecraig had the reputation of being stronger than that of Moffat. At Rutherford near Carlops there is a chalybeate well, "Heavenly Aqua"; another, "Philip’s Well," at Catslacknowe in Selkirk; and two at Bowerhope. Calcareous springs have been found in fifteen different places in Yarrow.