Ore

Ore is natural rock or sediment that contains one or more valuable minerals, typically including metals, concentrated above background levels, and that is economically viable to mine and process.

[5] Once processed, the gangue is known as tailings, which are useless but potentially harmful materials produced in great quantity, especially from lower grade deposits.

They can form in as little as one million years and are a source of iron (Fe), manganese (Mn), and aluminum (Al).

Iron rich water is thought to have upwelled where it oxidized to Fe (III) in the presence of early photosynthetic plankton producing oxygen.

[40][41] Placer deposits are the result of weathering, transport, and subsequent concentration of a valuable mineral via water or wind.

A placer deposit is considered alluvial if formed via river, colluvial if by gravity, and eluvial when close to their parent rock.

[44] They are formed by a combination of diagenetic and sedimentary precipitation at the estimated rate of about a centimeter over several million years.

The proposed mining of these nodules via remotely operated ocean floor trawling robots has raised a number of ecological concerns.

[1] Some ores contain heavy metals, toxins, radioactive isotopes and other potentially negative compounds which may pose a risk to the environment or health.

Tailings of particular concern are those of older mines, as containment and remediation methods in the past were next to non-existent, leading to high levels of leaching into the surrounding environment.

[51] Additional elements found in ore which may have adverse health affects in organisms include iron, lead, uranium, zinc, silicon, titanium, sulfur, nitrogen, platinum, and chromium.

[5] Ores such as those of sulphide minerals may severely increase the acidity of their immediate surroundings and of water, with numerous, long lasting impacts on ecosystems.

[5][53] When water becomes contaminated it may transport these compounds far from the tailings site, greatly increasing the affected range.

[52] Uranium ores and those containing other radioactive elements may pose a significant threat if leaving occurs and isotope concentration increases above background levels.

Radiation can have severe, long lasting environmental impacts and cause irreversible damage to living organisms.

[6] Until the 18th century gold, copper, lead, iron, silver, tin, arsenic and mercury were the only metals mined and used.