page_title: Dolaucothi Gold Mines
section_title: Opencast mining
hierarchical_section_title: Dolaucothi Gold Mines / Roman mining methods / Opencast mining
caption_attribution_description: English: Tank C above main opencast at Dolaucothi
context_page_description: The Dolaucothi Gold Mines, also known as the Ogofau Gold Mine, are ancient Roman surface and underground mines located in the valley of the River Cothi, near Pumsaint, Carmarthenshire, Wales. The gold mines are located within the Dolaucothi Estate which is now owned by the National Trust.
  They are the only mines for Welsh gold outside those of the Dolgellau gold-belt, and are a Scheduled Ancient Monument. They are also the only known Roman gold mines in Britain, although it does not exclude the likelihood that they exploited other known sources in Devon in South West England, north Wales, Scotland and elsewhere. The site is important for showing advanced Roman technology.
context_section_description: Prospecting was successful and several opencasts are visible below the large tanks built along its length. The only exception is the final and very large tank, below which are two reservoirs. It is likely that this complex was used for washing powdered ore to collect the gold dust.
  More leats and tanks can be found below the line of the main aqueduct, some of which are shown on the map of the site. They surround the lip of the very large opencast and the tank shown at right is one which was built on the main aqueduct. It was successful in finding a vein, judging by the opencast below, but must have been modified later to feed a washing table built to the left-hand side (near the figure in the picture), probably to wash the crushed ore from the same opencast working. It is labelled Tank C in the schematic diagram. Similar tanks occur below as the Romans followed the large vein down to the road and the main opencast. Most of the opencast workings must therefore be Roman in origin, since one of the aqueducts has been confirmed by carbon 14 dating as to predate all modern workings. Just by the road itself the Carreg Pumsaint has been erected in the space beside a large mound, now thought to be a dump of waste material from mining activities.
  The existing ponds above and below the minor road from Pumsaint to Caeo, were probably part of a cascade for washing ore, the upper tank having yielded large quantities of Roman pottery from c. AD 78 to at least 300 (Lewis, 1977; Burnham 2004). The upper pool is known as Melin-y-Milwyr, or the soldiers' mill, an intriguing name that implies that watermills may have been used here during the Roman period. Alternatively, it may have been a sequence of washing tables for the crushed gold ore. A large-scale mill complex is known from Barbegal in southern France, where no less than 16 mills (in two lines of 8 each) were built into the side of a hill and supplied with water from a single aqueduct. There were two lines of parallel overshot mills, the outflow from one feeding the next below. The mill supplied flour to the region. Moreover, Roman engineers used sequences of reverse overshot water-wheels to dewater mines, and the deep workings at Dolaucothi produced a fragment of such a wheel during the 1930s when deep mining operations were resumed. Sequences of such wheels increased the lift, and one extensive sequence of 16 wheels was found in old Roman mine workings on the Rio Tinto river in the 1920s. The wheels were arranged in pairs and could lift water about 80 feet (24 m) from the bottom of the mine there.
caption: Tank C above main opencast
exif: {}