Editing Ore (section)

=== Manganese nodules ===
[[Polymetallic nodules]], also called manganese nodules, are mineral [[concretion]]s on the [[sea]] floor formed of concentric layers of [[iron]] and [[manganese]] [[hydroxide]]s around a core.<ref>{{Cite journal |last=Huang |first=Laiming |date=2022-09-01 |title=Pedogenic ferromanganese nodules and their impacts on nutrient cycles and heavy metal sequestration |url=https://www.sciencedirect.com/science/article/pii/S0012825222002318 |journal=Earth-Science Reviews |volume=232 |pages=104147 |doi=10.1016/j.earscirev.2022.104147 |bibcode=2022ESRv..23204147H |issn=0012-8252}}</ref> They are formed by a combination of [[Diagenesis|diagenetic]] and sedimentary precipitation at the estimated rate of about a centimeter over several million years.<ref>{{Cite journal |last1=Kobayashi |first1=Takayuki |last2=Nagai |first2=Hisao |last3=Kobayashi |first3=Koichi |date=October 2000 |title=Concentration profiles of 10Be in large manganese crusts |url=https://linkinghub.elsevier.com/retrieve/pii/S0168583X00002068 |journal=Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms |language=en |volume=172 |issue=1–4 |pages=579–582 |doi=10.1016/S0168-583X(00)00206-8}}</ref> The average diameter of a polymetallic nodule is between 3 and 10&nbsp;cm (1 and 4 in) in diameter and are characterized by enrichment in iron, manganese, [[heavy metals]], and [[rare earth element]] content when compared to the Earth's crust and surrounding sediment. The proposed mining of these nodules via [[Remotely operated underwater vehicle|remotely operated]] ocean floor trawling robots has raised a number of ecological concerns.<ref>{{Cite news |last=Neate |first=Rupert |date=2022-04-29 |title='Deep-sea gold rush' for rare metals could cause irreversible harm |language=en-GB |work=The Guardian |url=https://www.theguardian.com/environment/2022/apr/29/deep-sea-gold-rush-rare-metals-environmental-harm |access-date=2023-11-28 |issn=0261-3077}}</ref>