Cobalt-rich Crusts Research Articles

High-traversability and efficient path optimization for deep-sea mining vehicles considering complex seabed environmental factors

In cobalt-rich crust regions, rapid and safe pathfinding is critical for the operation of Deep-Sea Mining Vehicles (DSMVs). However, existing pathfinding solutions rarely account for traversability predictions in complex mining environments and extensive map data often results in computational inefficiencies. This paper proposes a High-Traversability and Efficient Path Optimization (HTEPO) strategy designed to ensure safe navigation and rapid decision-making accounting for complex seabed environmental factors. Initially, we develop a traversability assessment model combining the Analytic Hierarchy Process (AHP) with the Fuzzy Comprehensive Evaluation (FCE) method. This model assigns traversability scores to map out high-risk and impassable areas effectively. We then introduce a novel map model that integrates these scores with Voronoi diagrams to reduce search space and improve computing efficiency, ensuring safer route selections. Further, based on traversability index and map model, an enhanced A∗ algorithm equipped with adaptive heuristic weights is utilized to swiftly identify high-traversability paths for the DSMVs. Finally, three case studies with different seabed mining environments validate the excellent performance of the proposed method over other major existing methods in terms of path safety and computational efficiency.

Unusual cobalt behaviors and enrichment in cobalt-rich crust from the Magellan seamounts in the Western Pacific

Marine cobalt-rich (Co-rich) crusts are submarine critical metal resources with high economic value. In this study, detailed in-situ fine-scale morphological, mineralogical, and geochemical analyses were conducted on Co-rich crust from the Western Pacific. The Co-rich crust can be divided into three layers: (1) Layer 1 is the oldest anthracite layer and contacts with the substrate, showing a very dense laminated/columnar texture. Layer 1 can be further divided into two distinct sublayers: a lower black, massive, dense sublayer (Layer 1–1) and an upper black-to-brown sublayer (Layer 1–2). (2) Layer 2 is porous and locally vuggy, and its pore space is filled with a large amount of silicate detrital minerals and clay minerals. (3) Layer 3, on the top, is black and dense, with a dendritic, columnar/laminated texture. Co is very unevenly distributed throughout the whole crust, with three distinct Co-rich areas. Layer 3 is a typical hydrogenetic crust and has not undergone late alteration. The main processes for Co enrichment are specific adsorption-oxidation on Mn-oxides and the structural incorporation of Co3+ into Mn-oxide phases. The average Co content of the Layer 3 is much higher than that of the other two layers. The presence of abundant detrital and clay minerals, along with high levels of Al, Si, and Ti in Layer 2, indicates the incorporation of terrigenous material, resulting in a high average growth rate. However, these processes are not conducive to Co enrichment. In the phosphatized Layer 1, fluctuations in element content are significantly greater than in the upper, non-phosphatized layers. Phosphatization has resulted in the partial decomposition of the initial Co-rich micro-layers, which may have reactivated and migrated Co, contributing to secondary Co enrichment.

The occurrence phases and enrichment mechanism of rare earth elements in cobalt-rich crusts from Marcus-Wake Seamounts

The occurrence phases and enrichment mechanism of rare earth elements in cobalt-rich crusts from Marcus-Wake Seamounts

Dissimilarity of megabenthic community structure between deep-water seamounts with cobalt-rich crusts: Case study in the northwestern Pacific Ocean

As anthropogenic disturbance on deep-sea seamount ecosystems grows, there is an urgent need for a better understanding of the biodiversity and community structure in benthic ecosystems, which can vary at local and regional scales. A survey of the benthic megafauna on two adjacent deep-water seamounts in the northwestern Pacific Ocean was conducted, which are covered by cobalt-rich crusts, to assess the biodiversity patterns and dissimilarity of assemblage composition. Based on a multidisciplinary dataset generated from video recordings, multibeam bathymetry data, and near-bottom currents, environmental and spatial factors impacting the megabenthic communities were explored. Results showed that these two deep-water seamounts were dominated by hexactinellids, crinoids, and octocorals. The seamounts were able to support diverse and moderately abundant megafauna, with a total of 6436 individuals classified into 94 morphospecies. The survey covered a distance of 52.2 km across a depth range of 1421–3335 m, revealing multiple distinct megabenthic assemblages. The megabenthic communities of the two deep-water seamounts, with comparable environmental conditions, exhibited similarities in overall density, richness, and faunal lists, while dissimilarities in the relative abundance of taxa and assemblage composition. No gradual depth-related change in terms of abundance, richness, or species turnover was observed across the two seamounts, despite the statistical significance of depth in structuring the overall communities. The spatial distribution of megabenthic communities displayed a discontinuous and patchy pattern throughout the two deep-water seamounts. This patchiness was driven by the interactive effects of multiple environmental factors. Near-bottom currents and microhabitat features were the primary drivers influencing their dissimilarities in megabenthic community structure. This case study on the megabenthic community structure of two adjacent seamounts with cobalt-rich crusts can serve as an environmental baseline, providing a reference status for the conservation and management of seamount ecosystems, particularly valuable for areas being considered for deep-sea mining.

Predicting the distribution of megabenthic communities on deep-water seamounts with cobalt-rich crusts in the Magellan Seamount Chain in the northwestern Pacific ocean

Deep-water seamount ecosystems are sensitive to human activities and have a slow recovery rate after being disturbed. Bottom trawling and potential deep-sea mineral extraction could severely damage benthic communities on seamounts and seriously impact deep-sea ecosystems. Inadequate knowledge of the distribution of megabenthos on seamounts or their community structure hinders deep-sea conservation and management. In this study, based on a multidisciplinary dataset generated from recordings taken by human-occupied vehicle (HOV) and remotely operated vehicles (ROVs) along transects and environmental variables, a range of megabenthic morphotaxa were observed on two adjacent deep-water seamounts and predicted using species distribution models (SDMs). Accordingly, based on the predicted distribution of each morphotaxon, five distinct communities were identified through cluster analysis. The results of SDMs showed that environmental variables varyingly impacted the distribution of different morphotaxa, among which the average velocity and eastness direction of near-bottom currents, bathymetric position index (BPI), and backscatter intensity exerted the most significant influence on megabenthic distribution patterns. The distribution of five distinct communities showed a similarity of community composition on the two deep-water seamounts, suggesting a potential connectivity between the two seamounts. The distribution of communities revealed the spatial characteristics of vulnerability of deep-water seamounts at the community level, which could provide a direct basis for marine spatial planning of deep-sea ecosystems.

A new approach for sample preparation to determine the multi-element composition of cobalt-rich crust samples by wavelength dispersive X-ray fluorescence spectrometry

A new approach for sample preparation to determine the multi-element composition of cobalt-rich crust samples by wavelength dispersive X-ray fluorescence spectrometry

ПАМЯТИ СЕРГЕЯ ИВАНОВИЧА АНДРЕЕВА (30.05.1934–06.02.2023)

The article is dedicated to the memory of the Honoured Geologist of Russia, Doctor of Geological and Mineralogical Sciences Sergei Ivanovich Andreev, an outstanding researcher of the mineral resources of the World Ocean. Since 1976, Sergei Ivanovich Andreev headed a new direction at the Institute – the study of deep-sea minerals, being the head of the department of geology of solid ocean minerals, working until his last day. For many years, Sergei Ivanovich carried out a huge amount of research related to the problem of studying and developing the mineral resources of the World Ocean. He participated in the development of plans and methodological support for expeditionary work in the World Ocean, and was one of the main authors of the scientific and methodological basis for the study and development of deep-sea minerals in the World Ocean – ferromanganese nodules, cobalt-rich crusts and polymetallic sulphides. He was a pioneer of a new scientific direction – “Metallogeny of the World Ocean”. Sergei Ivanovich was the Scientific Director of the state project “Mineral Resources of the World Ocean”, participated in the study and discovery of large accumulations of PMN and CMC, which were subsequently taken into account when selecting the Russian Application Areas in the Pacific Ocean. Sergei Ivanovich was the Editor-in-chief and compiler of the unique “Metallogenic Map of the World Ocean” at a scale of 1:10,000,000 and a great number of other maps of ocean minerals. He was the author and co-author of over 300 published works, including 17 monographs and encyclopaedic publications, and 8 atlases. The article presents biographical data, and highlights the scientific achievements and personal qualities of S. I. Andreev.

An innovative method for the efficient and selective extraction of Co, Ni, Cu, and Mn from oceanic cobalt-rich crusts by ammonium sulfate roasting: Behavior, roasting kinetics and mechanism

The exploitation of deep-sea mineral resources is an unavoidable choice for sustainable human development, given the diminishing or even depletion of land-based mineral resources and the increasing demand for critical metals in global industrialization. This work presents a new method for the selective extraction of Co, Ni, Cu, and Mn from oceanic cobalt-rich crusts through the ammonium sulfate roasting-water leaching process. The metal oxides in oceanic cobalt-rich crusts were transformed to sulfates or ammonium sulfate salts by sulfation roasting and then by selective decomposition roasting to transform Fe2(SO4)3 to Fe2O3, while the other metals remained in sulfate forms. Under the sulfation roasting temperature of 450 ℃ for 120 min and the mass ratio of (NH4)2SO4 to cobalt-rich crusts of 1.2:1, the decomposition roasting temperature of 650 ℃ for 90 min and the air flow rate of 2 L/min, the leaching efficiencies of Mn, Co, Ni, and Cu reached 98.3 %, 93.7 %, 88.7 %, and 66.3 %, while the Fe leaching efficiency was only 0.9 %. The analysis of the mechanism shows that the Mn in oceanic cobalt-rich crusts first formed (NH4)2Mn2(SO4)3 during roasting and then decomposed to MnSO4; Co, Ni, and Cu first formed (NH4)2Co2(SO4)3, (NH4)2Ni2(SO4)3, (NH4)2Cu3(SO4)4 and then decomposed to their respective sulfates; Fe first formed (NH4)3Fe(SO4)3 and finally decomposed to Fe2O3. Ammonia released during the roasting process can be absorbed with dilute sulfuric acid and then regenerated (NH4)2SO4 with an ammonia recovery of 87.3 %. The process proposed in this study is not only efficient, clean, and selective, but also achieves full component recovery from oceanic cobalt-rich crusts, with obvious environmental and economic advantages over the traditional reduction roasting-acid/ammonia leaching.

Seamount mining test provides evidence of ecological impacts beyond deposition.

In July 2020, Japan undertook the first deep-sea mining test of cobalt-rich crusts on the summit of Takuyo-Daigo Seamount within their exclusive economic zone (EEZ). Seabed mining regulations are currently being developed by the International Seabed Authority (ISA)1; however, a lack of experimental data has so far constrained our understanding of the associated impacts, particularly from the release of sediment plumes.2 The area of sediment re-deposition from the crust mining test was determined using modeled data and in situ observations. To investigate biological impacts, variations in seabed megafauna (animals>1cm) were quantified from seabed imagery collected around the excavation site before, 1month, and 13months after the test in areas both inside and outside (adjacent) expected deposition. Observable responses varied across community components: densities of sessile animals were similar between deposition and adjacent areas throughout the study; mobile epifauna were less abundant only in the deposition area following disturbance; and highly mobile swimmers showed reduced densities after the test in both deposition and adjacent areas following disturbance. These results stress that monitoring of highly mobile taxa may be essential to fully assess disturbance extent and magnitude. Fish may avoid areas even outside plume deposition, possibly owing to the creation of suboptimal feeding patches resulting from deposition. Our findings suggest sufficiently large (>300×300 m), distant, and representative control areas are essential to optimally map deep-sea mining impacts in ferromanganese crust habitats to ensure impact assessments encompass the full range of functional components in the megabenthic community (including mobile fishes) that typically inhabit seamounts.

Numerical Simulation Investigation on Parameter Optimization of Deep-Sea Mining Vehicles

The four-track walking mining vehicle can better cope with the complex terrain of cobalt-rich crusts on the seabed. To explore the influence of different parameters on the obstacle-crossing ability of mining vehicles, this paper took a certain type of mine vehicle as an example and establish a mechanical model of the mine vehicle. Through this model, the vehicle’s traction coefficient variation could be analyzed during the obstacle-crossing process. It also reflected the relationship between the obstacle-crossing ability and the required traction coefficient. Many parameters were used for this analysis including the radius of the guide wheel radius, ground clearance of the driving wheel, the dip angle of the approaching angular and the position of centroid. The result showed that the ability to cross the obstacles requires adhesion coefficient as support. When the ratio between obstacle height and ground clearance of the guide wheel was greater than 0.7, the required adhesion coefficient increased sharply. The ability to cross obstacles will decrease, if the radius of the guide wheel increases, the height of the driving wheel increases or the dip angle of the approaching angular increases. It was most beneficial to cross the obstacle when the ratio of the distance between the center of mass and the front driving wheel to the wheelbase is between 0.45‒0.48. The results of this paper could provide reference for structural parameter design and performance research for mining vehicles.

One of the Deepest Genera of Antipatharia: Taxonomic Position Revealed and Revised

The genus Abyssopathes Opresko, 2002, comprises deep-sea black corals known almost exclusively from lower bathyal and abyssal depths, mainly from seamounts covered by cobalt-rich crusts and areas of polymetallic nodules. The taxonomical position of the genus and its placement in the family Schizopathidae has been repeatedly questioned, but fruitlessly. Known only in extremely deep habitats, these corals have rarely been collected in a state suitable for morphological or molecular studies that could help to clarify their status. Recently, increasing attention has been paid to the study of fauna associated with deep-sea minerals. Using material of Abyssopathes lyra (Brook, 1889) sampled during these studies, we transfer the genus Abyssopathes from the family Schizopathidae to the family Cladopathidae based on morphological and molecular data. Morphological data includes six mesenteries in the polyps, a unique pinnulation pattern found only in genera within the Cladopathidae, and relatively short polyp tentacles, a feature typical of some cladopathids. Sequencing data, consisting of 626 bp from the mitochondrial cox1 gene, showed that Abyssopathes is 99% identical to Chrysopathes Opresko, 2003, Cladopathes Brook, 1889, Heteropathes Opresko, 2011, and Trissopathes Opresko, 2003 (all Cladopathidae), in this gene region.

Study on Sound Velocity and Attenuation of Underwater Cobalt-Rich Crust Based on Biot and BISQ Theories

A prediction model of the sound velocity and sound attenuation of underwater cobalt-rich crusts (CRCs) was established to solve the problem that it is difficult to predict the sound velocity in thickness measurements of cobalt-rich crusts. Based on Biot theory and BISQ theory, a simplified Biot and BISQ model was proposed for the prediction of the sound velocity and sound attenuation of CRCs by using the Kozeny–Carman (KC) equation. The models could calculate the sound velocity and attenuation by the porosity and detection frequency. Based on the physical and mechanical properties of CRCs, a similarity model of the sound velocity and sound attenuation of CRCs was made by using the similarity theory to solve the problem that it is difficult to measure the acoustic propagation characteristics of CRCs. The sound velocity and sound attenuation of CRC similarity models with different porosities were measured by an underwater transmission experiment and the results of the simplified model calculation and experimental measurements were compared. The results showed that the simplified Biot model was suitable for the CRC sound velocity prediction and the simplified BISQ model was suitable for the CRC sound attenuation prediction, which had a high prediction accuracy.

A Method for Assessing the Thickness of Cobalt-Rich Crust on Seamounts and Its Application on the Il’ichev Guyot

Seamount cobalt-rich crusts are rich in cobalt resources and are sought after worldwide. Among different affecting parameters, crust thickness is the most important in evaluating cobalt-rich crust resources in seamounts. Generally, there are two challenges to crust thickness evaluation: firstly, due to high operating costs, most geological stations for seamount exploration have sparse sampling distributions so there are insufficient data to estimate the crust thickness distribution; secondly, a single evaluation method has advantages and disadvantages, and it is not feasible to benefit from the advantages only. These methods cannot simultaneously make full use of the sampling data in local areas, providing a more appropriate evaluation of the whole area. As a result, the estimated results cannot fully reflect the thickness distribution. Based on the thickness data of the station survey and topographic data, geostatistical units are divided, and a comprehensive crust thickness assessment scheme is established on the ArcGIS platform. To this end, the adjacent area method is applied to calculate the crust thickness within the influence range of the station. Combined with the station buffer radius and Thiessen polygon method, the crust thickness within 1.5 km of the survey station was estimated. Then the “slope–distance” Kriging interpolation method was used to calculate the crust thickness in the study area, and the crust thickness in the optimal effective radius area was given to compensate for the missing part in the first step. Finally, the geological blocks were divided using the topographic classification method, and the crust thickness of the remaining unassigned regions was estimated using the mathematical expectation method. The proposed method was applied to evaluate the Il’ichev Guyot’s crust thickness and reasonable results were achieved. It was found that the thickness estimation of the area near the station is consistent with the measured values. Since finer topographic data are used in the calculation, the thickness estimation result is more detailed. In this regard, a simple and effective calculation method was established on the ArcMap platform. The mathematical expectation estimation method of the crust thickness, based on the topographic and geomorphological classification from the perspective of the mineralization mechanism, compensates for the drawbacks of the first two methods originating from the lack of data points. The results show that the proposed method is an appropriate scheme to evaluate seamount crust thickness without comprehensive investigation.

A Study on the Performance Modeling Method for a Deep-Sea Cobalt-Rich Crust Mining Vehicle

To mine the cobalt-rich crust deposits at the substrate of the slope of the seamount, the mining vehicle needs to walk on the slope and strip the cobalt-rich crust from the substrate. To achieve safety and control, the vehicle needs to stably walk on the slope. In this paper, we propose a modeling method for mining vehicle performance based on slope stability and antislip and antiskid conditions. The specific energy of three types of mining vehicles is compared based on dimensionless parameters. The dual-drum type is determined to be the best choice in terms of energy costs, followed by the down-milling type. The performance of the compact mining vehicle based on different slope angles and two sea trial results in the South China Sea indicate that the slope angle, substrate, and crust have significant effects on the stability. The modeling method proposed in this paper can help designers estimate the structure and power of mining vehicles based on mining stability.

The Significance of Nanomineral Particles during the Growth Process of Polymetallic Nodules in the Western Pacific Ocean.

As a huge reservoir of economic metallic elements, oceanic polymetallic nodules have important strategic significance and are one of the main research objects in marine geology, especially their formation process and genetic mechanism. In this study, polymetallic nodules from the cobalt-rich crust exploration contract area in the Western Pacific Ocean were taken as the research object. Optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive spectroscopy (EDS) were used for observation and testing. The results indicate that many nanomineral particles, mainly composed of Fe and Mn, developed in polymetallic nodules from the western Pacific Ocean. The solid-liquid interface process of nanomineral particles plays an important role in the growth and evolution of nodules. We propose that the growth process of polymetallic nodules in the western Pacific Ocean can be divided into three stages. First, terrigenous detritus nucleates, and nanomineral particles composed of Fe, Mn, and other elements form, aggregate and attach to the core to form the initial shell. Second, a dense layer of the shell forms under stable conditions. In the third stage, the redox conditions of the nodules change, and the polymetallic nodules experience a variety of interface process modifications.

Effects of confining pressure and cutting sequence on the cobalt-rich crust cutting mechanism by using conical picks in ocean environments

Confining pressure and cutting sequence of conical picks directly affect the ocean mining efficiency. The simulation model of cobalt-rich crust cutting with two-dimensional discrete element method is established to simulate the whole process of crack growth. According to the obtained crack growth patterns and the rules of fracture-block formation, four typical fracture modes are summarized, and the fracture mechanism is further studied from three aspects: the efficiency of cobalt-rich crust cutting, the ability of crack growth and the size of fracture-block. The results show that with the increase of confining pressure, the cutting efficiency and crack growth ability decrease, and the cutting efficiency of simultaneous loading is larger than that of the sequential loading, while the crack growth ability is just the opposite. In addition, the size of fracture-block is related to fracture modes.

Research on Recovery of Valuable Metals from Cobalt-Rich Crust Using Carbon as a Reduction Agent during the Acid Baking Process

Cobalt-rich crust is a seabed metal mineral resource that is different from oceanic polymetallic nodules. Based on the higher Co content than polymetallic nodules, the commercial value of cobalt-rich crust may be better than that of polymetallic nodules. Due to the special distribution of valuable metals, commercial implementation is always limited. Herein, a novel process is proposed to efficiently and, in an eco-friendly way, recycle valuable metals from cobalt-rich crust. The results indicate that carbon could promote the decomposition of manganite in the cobalt-rich crust during the acid baking process, and the leaching ratio of Mn could increase by 50% when carbon is added during acid baking. In addition, it can be found that the promotion of carbon for Co is stronger at low sulfuric acid consumption than that at high sulfuric acid consumption; however, there is no promotion of carbon for leaching Ni and Cu during the acid baking process. The leaching ratio of Ni, Co, Cu, Mn, and Fe reached 98.59%, 91.62%, 93.81%, 41.27%, and 26.94%, respectively, when the mass ratio of the sulfuric acid and cobalt-rich crust was 0.567, the mass ratio of the carbon and cobalt-rich crust was 0.1, the temperature was 200 °C and the time was 240 min. This research could provide an alternative economic process for recycling valuable metals from cobalt-rich crusts.

Marine minerals’ role in future holistic mineral resource management

Abstract Deep marine mineral deposits are mineral deposits that have been formed outside the continental slope. Currently three main types of deposits are generally recognized: polymetallic manganese nodules, massive seafloor sulfides and cobalt-rich crusts. The authors argue that marine mineral resource management must be holistic. Holistic marine mineral management requires a clear understanding of the objectives to be achieved through mining and to assess and ensure a proper balance between costs, risks, potential gains and losses. For decades there have been substantial uncertainties regarding the short- and long-term impact of deep-sea mining on international society and the economy and, more recently, environmental issues have become central to the debate over mining the deep seabed. If deep-sea mining is to play a constructive role in the green transition towards more environmentally robust energy production and e-mobility, more ambitious interdisciplinary research is needed to provide the knowledge needed to devise a holistic approach to management of marine minerals. This includes completing thorough baseline studies in conjunction with geological exploration and devising new means of handling financial and technological uncertainties when making investment decisions and when developing regulatory frameworks.

Exploring Ocean Floor Geodiversity in Relation to Mineral Resources in the Southwest Pacific Ocean

The future extraction of mineral resources may irreversibly damage ocean floor geodiversity in the Southwest Pacific Ocean. Therefore, understanding of the spatial distribution of ocean floor geodiversity in relation to mineral resources is important. For that purpose, we first developed a geodiversity index map of the western Pacific Ocean including spatial information of openly available digital layers of four components: seafloor geomorphology, sediment thickness, bathymetry and seafloor roughness. Second, we analysed how these components contributed to the geodiversity index. Finally, correlations between three mineral resources (seafloor massive sulphides, polymetallic nodules and cobalt-rich crusts) and the geodiversity index, its components, and the ocean floor age were calculated. The results showed that the ocean floor environment and the time necessary for the formation of the three mineral resources were predominantly related to the bathymetry component and the age of the ocean floor, and to a lesser extent to the seafloor roughness, geomorphology and sediment thickness components. We conclude that the ocean floor geodiversity index and its components contribute to an improved understanding of the spatial distribution of abiotic seafloor diversity and can be optimized by using higher resolution data. We suggest that ocean floor geodiversity could be considered in future resource extraction to support responsible mining and help limit environmental damage.

Seabed mining and blue growth: exploring the potential of marine mineral deposits as a sustainable source of rare earth elements (MaREEs) (IUPAC Technical Report)

Abstract The expected growth of the global economy and the projected rise in world population call for a greatly increased supply of materials critical for implementing clean technologies, such as rare earth elements (REEs) and other rare metals. Because the demand for critical metals is increasing and land-based mineral deposits are being depleted, seafloor resources are seen as the next frontier for mineral exploration and extraction. Marine mineral deposits with a great resource potential for transition, rare, and critical metals include mainly deep-sea mineral deposits, such as polymetallic sulfides, polymetallic nodules, cobalt-rich crusts, phosphorites, and rare earth element-rich muds. Major areas with economic interest for seabed mineral exploration and mining are the following: nodules in the Penrhyn Basin-Cook Islands Exclusive Economic Zone (EEZ), the Clarion–Clipperton nodule Zone, Peru Basin nodules, and the Central Indian Ocean Basin; seafloor massive sulfide deposits in the exclusive economic zones of Papua New Guinea, Japan, and New Zealand as well as the Mid-Atlantic Ridge and the three Indian Ocean spreading ridges; cobalt-rich crusts in the Pacific Prime Crust Zone and the Canary Islands Seamounts and the Rio Grande Rise in the Atlantic Ocean; and the rare earth element-rich deep-sea muds around Minamitorishima Island in the equatorial North Pacific. In addition, zones for marine phosphorites exploration are located in Chatham Rise, offshore Baja California, and on the shelf off Namibia. Moreover, shallow-water resources, like placer deposits, represent another marine source for many critical minerals, metals, and gems. The main concerns of deep-sea mining are related to its environmental impacts. Ecological impacts of rare earth element mining on deep-sea ecosystems are still poorly evaluated. Furthermore, marine mining may cause conflicts with various stakeholders such as fisheries, communications cable owners, offshore wind farms, and tourism. The global ocean is an immense source of food, energy, raw materials, clean water, and ecosystem services and suffers seriously by multiple stressors from anthropogenic sources. The development of a blue economy strategy needs a better knowledge of the environmental impacts. By protecting vulnerable areas, applying new technologies for deep-sea mineral exploration and mining, marine spatial planning, and a regulatory framework for minerals extraction, we may achieve sustainable management and use of our oceans.