Ancient Roman Mining and Quarrying Techniques
Read this article about Roman mining to learn how ancient Romans solved its technical problems. They even had mechanical devices for removing modest amounts of water from mineshafts.
Mining Techniques
Opencast Mining
Figure 3: Dolaucothi gold mine adit
This method involved extracting ore from the ground's surface by using flowing water to wash away organics, or mining the side of an open rock face. It was the easiest and safest method and did not require miners to face the dangers of underground mining. Opencast was done to obtain gold ore from 'placer' deposits which are found in the slower areas of streams. Gold sinks to the bottom of a river due to its high density and will accumulate where the water is slowest because it spends more time there. Pliny notes the high quality of opencast ores in rivers and streams: "No gold is more refined, for it is thoroughly polished by the very flow of the stream and by wear".
Opencast was also performed on dry surfaces, Roman miners simply brought water with them since it was so helpful with this method. In the case of the Dolaucothi mines, the nearby Cothi river was used to bring water by aqueduct. Tanks were built directly above the placer deposits to hold enough water to wash away the top organic layer of soil and expose the gold ore in a technique known as hushing. The running water also helped Romans by giving them a convenient way to wash away impurities from the ore before sending it to the smelter (Greene, 1986). Romans dug tunnels only when ore was far underground and it was considered worth it, the hazards of tunneling were learned on a trial and error basis.