Crystal Mining vs. Industrial Mining
Share
Crystal mining is not to be confused with industrial mining, it is comparatively rare and always done on a small scale.
Crystal and mineral specimens can be very delicate and may be destroyed by the techniques currently in practice in industrial mining. Instead, they are harvested by a few people, most often family groups, who carefully remove the specimens by hand which can be a slow and dangerous process.
Colombian quartz, for example, is extracted by retired emerald miners from old emerald mines that are no longer productive. The miners work for themselves and retain the profits from what they sell. In other places, such as Namibia, locals enter disused mines to take a few crystals to sell to tourists.
Mining for precious gemstones, such as ruby, sapphire and emerald, differs from much of the mining that produces other crystals and minerals. There are two main types of deposit, usually referred to as primary and secondary. Most gemstone deposits are discovered by accident. Primary deposits are located in the original host rock.
The crystals are generally in good condition, but in most cases the yield will be relatively small, with many tons of “deaf” rock (non-gem bearing rock) having to be removed in the search for gemstones. Crystals from primary deposits are removed with hand tools, pneumatic tools, or by blasting.
Secondary deposits (also known as alluvial deposits) occur when gemstones have been transported from their place of formation, and deposited elsewhere via river, sea, coastal erosion, or even wind. The crystals are usually more rounded, and smaller, than those from primary deposits, but occur in greater concentrations. When prospecting in riverbeds, various sluiceways and dams are used to create particular water-flow conditions that will expose the gemstones. If a secondary deposit is beneath a surface layer (known as a placer deposit), either this layer is removed, or a shaft is built downwards. With minimal bracing, these shafts can be up to 10m deep.
As far as the environmental impact of gemstone mining is concerned, only diamond mining is done on a truly industrial scale and employs open pit as well as deep hole methods. This is because of the way diamonds form and, therefore, where they are found. Diamonds are believed to form in specific areas of the Earth’s upper mantle where there is adequate heat and pressure (at least 90 mi / 150 km below the surface). Pieces of diamond-bearing mantle are torn out and delivered to the surface by rare, deepsource volcanic eruptions – an ancient type of eruption which has not occurred for millions of years. The magma is propelled upwards at high velocity, then slows and solidifies as it nears the surface, forming a volcanic pipe of kimberlite or lamproite. The easiest way to extract the diamonds from the volcanic pipe is to strip it away from the surface down.
