Atmospheric CO₂ (carbon dioxide) concentrations have reached unprecedented levels in human history, surpassing 423.6 ppm in 2023 from a preindustrial level of 280 ppm. This increase has occurred at a rate of approximately 2.3 ppm per year over the past decade, which is about 100 times faster than natural variations ^[1][2][1,2]. The primary driver behind the rising CO₂ concentrations is the extensive use of fossil fuels, leading to an enhanced greenhouse effect that elevates global average temperatures and impacts various systems, including climate, ecology, and society. To mitigate these effects, the 2015 Paris Agreement sets a target of limiting anthropogenic warming to 1.5–2 °C ^[3][4][3,4]. Consequently, it is crucial to find solutions that effectively and consistently reduce the net flow of CO₂ into the atmosphere while ensuring the fulfillment of energy requirements ^[5][6][5,6]. The International Energy Agency suggests that the goals of the Paris Agreement can be accomplished by maximizing the practical limits of existing climate-mitigation technologies [7]. These climate-mitigation techniques include submitting Nationally Determined Contributions (NDCs) that outline specific emission reduction targets and strategies, transitioning to renewable energy sources, enhancing energy efficiency, implementing carbon pricing mechanisms, promoting carbon capture and storage (CCS), conserving and restoring forests, and prioritizing adaptation and resilience measures. The Paris Agreement recognizes the need for comprehensive and ambitious actions to address climate change and promote a sustainable future [8].

Numerous geological systems worldwide possess the capacity to securely retain CO₂ captured from industrial activities for centuries ^[9][10][9,10]. Basalt formations possess superior CO₂ storage efficiency compared to other geological formations, thanks to their remarkable reactivity, widespread availability, and geological durability ^[11][12][13][11,12,13]. The reactive minerals found in basalt facilitate rapid and effective mineral carbonation, enabling efficient storage of CO₂ ^[7][14][7,14]. Additionally, the abundance of basalt deposits worldwide offers ample opportunities for large-scale implementation of CO₂ storage initiatives ^[15][16][17][15,16,17]. Basalt’s structural stability and long-term resilience make it an appealing choice for long-term CO₂ storage, contributing significantly to global efforts to reduce greenhouse gas emissions and combat climate change ^[18][19][20][18,19,20]. Basalt’s capacity to permanently sequester CO₂ makes it an appealing choice for carbon capture and storage (CCS) strategies ^[21][22][21,22]. Once the CO₂ is stored in basalt formations, it remains trapped within the mineralized rock, preventing its re-emission into the atmosphere ^{[20][23][24][25]}[20,23,24,25]. There are certain limitations and uncertainties associated with the CO₂ storage in basalt; however, its potential of rapid mineralization and carbonation instills confidence in the efficacy of basalt reservoirs as a viable solution for mitigating greenhouse gas emissions ^[26][27][26,27]. Moreover, basalt formations offer geological stability and containment integrity. Basalt is known for its variable permeability, reducing the risk of CO₂ leakage ^[27][28][27,28]. The dense structure of basalt hinders the migration of CO₂ through fractures, ensuring the confinement of the stored CO₂ within the reservoir ^[29][30][29,30]. This geological stability enhances the safety and security of the storage operation ^[31][32][31,32].

The reactivity of minerals plays a crucial role in the process of CO₂ carbonation, which has significant implications for mitigating climate change and developing sustainable carbon capture and storage technologies ^[33][34][33,34]. Carbonation involves the chemical reaction between CO₂ and minerals to form stable carbonate compounds. The reactivity of minerals determines the rate and extent of this carbonation process ^[35][36][37][35,36,37]. Minerals that possess high reactivity towards CO₂ are desirable for efficient carbonation [38]. These reactive minerals, such as olivine, serpentine, or certain types of basalt, contain elements like magnesium, calcium, or iron, which readily react with CO₂ to form solid carbonate minerals [39]. The carbonation reaction involves the dissolution of CO₂ in water to form carbonic acid (H₂CO₃), which then reacts with the mineral surface to release metal cations (e.g., Mg²⁺, Ca²⁺, Fe²⁺) and form stable carbonate minerals (e.g., magnesium carbonate, calcium carbonate, iron carbonate) [40].

The role of mineral reactivity in CO₂ carbonation is twofold. Firstly, highly reactive minerals accelerate the rate of carbonation, facilitating the capture and conversion of CO₂ into stable carbonate compounds ^[41][42][41,42]. This fast carbonation kinetics are desirable for efficient carbon capture and storage systems, as they enable a rapid transformation of CO₂ into solid forms, effectively immobilizing it and reducing its potential for atmospheric release ^[43][44][43,44]. Secondly, the reactivity of minerals affects the overall carbonation capacity ^[45][46][47][45,46,47]. Minerals with higher reactivity can sequester more CO₂ by providing a larger surface area for reaction and a greater availability of reactive sites The overall carbonation capacity of minerals is influenced by their reactivity, which determines how effectively they can chemically react with CO₂ to form stable carbonate compounds. Minerals with higher reactivity possess a greater ability to absorb and sequester CO₂ through carbonation [48]. In context of intrinsic reactivity, surface area, and in situ mineralization, it is important to understand that minerals with higher reactivity have the potential to sequester more CO₂. This is due to their larger surface area, which provides increased availability of reactive sites. However, it is crucial to recognize that intrinsic reactivity is influenced by factors such as mineral composition and crystal structure. Moreover, the surface area of minerals plays a significant role in facilitating the contact between CO₂ and minerals, influencing the carbonation reaction rate and overall efficiency. This understanding is particularly relevant in the context of in situ mineralization, as the assessment of carbonation potential within geological formations relies on considerations of intrinsic reactivity and surface area [49]. Understanding and optimizing the reactivity of minerals in CO₂ carbonation are vital for advancing carbon capture and storage technologies. Researchers are actively investigating methods to enhance mineral reactivity, such as mechanical activation, thermal treatment, or chemical pre-treatment ^[50][51][50,51]. These techniques aim to increase the surface area, modify the mineral structure, or introduce catalytic additives to improve the efficiency of carbonation processes.

Despite the importance of the reactivity of basalt minerals in the carbonation and mineralization process, thorough study on the reactivity of the minerals present in different kinds of basalt is lacking. The development of efficient carbon capture and storage methods is hampered by our inadequate understanding of particular mineralogical compositions and their related reactivity potentials. Therefore, there is a critical information vacuum regarding the detailed research of basalt minerals and their reactivity, which hinders the optimization of carbon sequestration technology and restricts our capacity to successfully battle climate change.

CO₂ sequestration in basalt involves various routes and methods that leverage the reactivity of basaltic minerals to capture and store carbon dioxide. Here are some different routes for CO₂ sequestration in basalt.

In Situ Mineral Carbonation: In this method, CO₂ is injected deep into underground basalt formations that are porous and permeable. Once injected, the CO₂-rich fluids come into contact with the minerals in the basalt, leading to a series of chemical reactions. The CO₂ dissolves in water to form carbonic acid, which reacts with minerals like olivine, pyroxenes, and feldspars in the basalt. These reactions result in the formation of stable carbonate minerals, such as calcite, magnesite, and serpentine. These carbonates are securely stored in the geological formations, effectively sequestering the captured CO₂ [52].

Enhanced Weathering: Enhanced weathering aims to accelerate the natural weathering process of basaltic rocks by exposing them to the atmosphere and CO₂-rich fluids. This can be achieved by spreading crushed basalt on land surfaces or using ocean-based platforms to increase exposure. Rainwater or CO₂-enriched solutions interact with the basaltic minerals, leading to mineral dissolution and the subsequent formation of carbonate minerals. The carbonation reactions lock up the CO₂ in stable mineral forms [53].

Direct Injection into Basalt Aquifers: Injection of CO₂ into deep underground basalt aquifers involves injecting CO₂ into formations that already contain water. The injected CO₂ dissolves in the water, creating carbonic acid that reacts with the minerals in the basalt. This reaction leads to the dissolution of minerals and the precipitation of carbonate minerals, which are stored in the aquifer over time ^[54][55][54,55].

Subsurface Injection with Hydrothermal Activation: This method combines CO₂ injection with the injection of hot water into basalt formations. The heat from the injected water enhances the reactivity of the minerals in the basalt, leading to faster dissolution and carbonation reactions. Hydrothermal conditions accelerate the mineral carbonation reactions and can improve overall carbon capture efficiency [56].

Ocean-Based Sequestration: Some proposals suggest grinding basaltic rocks into fine particles and dispersing them in the ocean. The fine particles react with dissolved CO₂ in seawater to form carbonate minerals. This process can contribute to ocean carbon sequestration and potentially mitigate ocean acidification [57].

Hydrothermal Mineralization: Hydrothermal processes involve subjecting basaltic rocks to high-temperature and high-pressure conditions. These conditions promote rapid mineral dissolution and the subsequent formation of carbonate minerals. Hydrothermal mineralization may be applicable in regions where suitable geothermal resources are available [58].

Coupling with Geothermal Energy: Basalt formations with access to geothermal resources can use the heat from these resources to accelerate mineral carbonation reactions. Geothermal fluids are utilized to heat water, enhancing the reactivity of basaltic minerals and promoting the formation of carbonate minerals [59].

Hydraulic Fracturing and CO₂ Injection: In this approach, hydraulic fracturing techniques are employed to create fractures in basalt formations. These fractures provide pathways for the injection of CO₂-rich fluids. The injected CO₂ interacts with the minerals in the fractured basalt, leading to mineral carbonation reactions [60].

The geochemistry of basalt plays a crucial role in the storage of CO₂, as it possesses natural properties that enable the capture and sequestration of CO₂. Basalt exhibits a remarkable ability to react with CO₂ and form stable carbonate minerals, a process known as mineral carbonation or carbon sequestration. This phenomenon is highly significant in the context of addressing climate change and reducing greenhouse gas emissions. Basaltic rocks contain reactive minerals that readily interact with CO₂, including calcium, magnesium, and iron-bearing minerals. These minerals can undergo dissolution and reprecipitation reactions when exposed to CO₂, resulting in the transformation of CO₂ into solid carbonate compounds. This process effectively stores the CO₂ over extended periods, providing a means of long-term carbon sequestration.

Water–rock interactions are critical for mineral carbonation to occur. Basalt acts as a host rock, allowing water and dissolved CO₂ to infiltrate its structure. This interaction enables the dissolution of basalt minerals and subsequent precipitation of carbonate minerals. Furthermore, the geochemical composition of basalt is conducive to mineral carbonation. The presence of calcium, magnesium, and iron-bearing minerals in basalt provides the necessary chemical elements for the formation of stable carbonate minerals. The compatibility of basalt’s geochemistry with the carbonation process makes it an ideal candidate for CO₂ storage.

The utilization of basalt geochemistry for CO₂ storage involves injecting CO₂ into deep basalt formations, where the natural reactions with the rock can lead to the permanent sequestration of CO₂ in the form of stable carbonate minerals. This approach has gained considerable attention as a potential method for carbon capture and storage, as well as CO₂ removal, offering a promising solution to mitigate greenhouse gas emissions and combat climate change. Various studies have been conducted that discussed the dissolution potential of various basaltic minerals and effect of grain size on CO₂ sequestration as shown in Table 13. The findings of the studies in Table 13 have been further explored in the development of M.H. reactivity scale for carbonation reactions in basalt.

In this section, the step-by-step carbonation reactions occurring in basalt for different minerals will be discussed. The carbonation process involves the reaction of CO₂ with minerals present in basalt, leading to the formation of carbonate minerals. The initial steps of CO₂ dissolution are universally observed in all carbonation reactions. However, the subsequent reactions and mineral products can vary depending on the specific minerals present in the basalt. A detailed exploration of the reactions involved in the carbonation of different minerals found in basalt will be provided, shedding light on the transformative process and its significance in carbon sequestration efforts.

The first step of CO₂ dissolution is fundamental and occurs universally in all types of minerals found in basalt during the carbonation process. These initial stages lay the foundation for subsequent reactions and mineral transformations. The introduction of CO₂ into basalt formations can be achieved through direct injection or by dissolving it in water prior to injection. This process begins with the dissolution of CO₂ in water, leading to the formation of carbonic acid. The formation of carbonic acid is influenced by various factors, including pressure, temperature, and salinity. As carbonic acid is generated, it alters the pH of the in situ water, enhancing its reactivity. This heightened reactivity prompts the hydrogen ions (H⁺) in the solution to interact with the basalt glass and dissolve the primary minerals present in the rock matrix, liberating cations like calcium (Ca²⁺)^, magnesium (Mg²⁺), and iron (Fe²⁺) into the solution. This elucidates the pivotal role played by the reactivity of carbonic acid in the process of mineral dissolution and subsequent release of cations during CO₂ injection into basalt formations [14]. These early steps play a crucial role in creating the chemical environment necessary for further interactions and the eventual formation of carbonate minerals ^[75][163]. While the subsequent reactions may differ depending on the specific mineral composition of the basalt, these initial two steps provide a common starting point for the carbonation process in all mineral types within basalt ^[76][77][164,165].

Step 1: CO₂ dissolution

Different minerals within basalt, such as olivine, plagioclase, pyroxene, spinel, and others, exhibit distinct chemical reactions as they undergo carbonation in following steps, which are tabulated in Table 24.

During the carbonation process, the minerals present in basalt undergo weathering, leading to their dissolution. This step involves the interaction between the mineral surface and the surrounding solution, resulting in the release of metal ions and the formation of silicate species. The specific reactions vary depending on the mineral type.

In this step, the metal ions released during the weathering process react with bicarbonate ions present in the solution. These reactions contribute to the overall carbonation process by forming carbonate minerals.

In this step, the carbonate minerals precipitate from the solution as a result of the reactions between metal ions and bicarbonate ions. The specific carbonate minerals formed depend on the availability of metal ions and the prevailing conditions.

CO₂ storage in alkaline basalt is particularly influenced by the mineralogy of the rock and specific factors that impact mineral reactivity. Alkaline basalts is characterized by the presence of minerals such as plagioclase feldspar, clinopyroxene, and olivine, which play a crucial role in the carbon sequestration process. Plagioclase, a key mineral in alkaline basalts, exhibits high reactivity and can rapidly react with CO₂ to form stable carbonate minerals ^[82][83][169,170]. Olivine and clinopyroxene also contribute to the overall reactivity, although their carbonation rates may vary and require specific conditions or longer reaction times.

The mineralization reactions involved in CO₂ storage for alkaline basalts primarily include the dissolution of minerals and the subsequent precipitation of carbonate minerals. Dominant minerals are olivine and pyroxene and the key mineralization reactions that occur during the carbonation process are tabulated in Table 24.

The dissolved calcium ions and bicarbonate ions react to form calcium carbonate (CaCO₃), water (H₂O), and release CO₂. These mineralization reactions involve the transformation of CO₂ into stable carbonate minerals, effectively sequestering CO₂ in a solid form within the alkaline basalt formations. It is important to note that the reactions mentioned above are simplified representations of the complex processes occurring during mineral carbonation. The actual reactions and reaction rates can be influenced by various factors, including temperature, pressure, fluid composition, and the specific mineralogy of the alkaline basalts ^[84][171].

Several factors influence the reactivity of minerals in alkaline basalts and, consequently, the efficiency of CO₂ storage. Here are some specific values and considerations for these factors:

Temperature and Pressure: The reactivity of minerals in alkaline basalts increases with higher temperatures. Typically, mineral carbonation reactions occur more rapidly at elevated temperatures. Optimal temperatures for efficient carbonation of olivine range from 150 to 300 degrees Celsius ^[85][172]. Mostly, alkaline basalts are present in the upper layer of the Earth’s crust so it can undergo carbonation at atmospheric pressure, i.e., 1 atm. However, the basalt located deep in the Earth’s crust or in the subduction zone may undergo carbonation at higher pressures ranging to a few hundred MPa. However, extreme pressures can affect the mineralogical composition and physical properties of basalt, potentially impacting reactivity ^[86][173].

Dissolution Rate: Alkali basalt contains 30-45% plagioclase, and plagioclase have the highest dissolution rates as depicted in Table 32 compared to olivine and pyroxene.

Fluid Composition: The composition of fluids interacting with alkaline basalts affects mineral reactivity. Fluids rich in dissolved CO₂ and alkaline ions, such as calcium and magnesium, enhance mineral dissolution and the subsequent precipitation of carbonate minerals ^[87][174].

Fluid pH and Redox Conditions: The pH of the fluid is a crucial factor in mineral reactivity. In the case of alkaline basalts, slightly alkaline to neutral pH conditions (pH 7 to 9) generally favor mineral carbonation. Redox conditions, such as the presence of oxidizing or reducing agents, can influence the stability and reactivity of minerals but are typically controlled within a range suitable for carbonation ^[88][175].

Grain Size and Surface Area: Alkali basalt have dominant percentage of plagioclase. According to Table 32, plagioclase demonstrates high reactivity due to its smaller grain size and larger surface area, making it particularly favorable for carbonation processes.

Rock Composition: The specific mineralogical composition of alkaline basalts affects its reactivity. Basalts rich in olivine minerals, with a higher olivine content and reactive mineral pyroxene, generally exhibit greater reactivity and higher carbon storage potential ^[89][176].

Geological Setting: The geological setting influences the availability of fluids and other factors that impact mineral reactivity. Basaltic formations in hydrothermal areas or areas with enhanced fluid circulation are more favorable for mineral carbonation reaction ^[90][177].

The mineralization reactions that occur in tholeiitic basalts during CO₂ storage involve the dissolution of certain minerals and the subsequent precipitation of carbonate minerals. Here are the detailed mineralization reactions that occur:

Tholeiitic basalts typically contain minerals such as plagioclase feldspar, pyroxene (including augite and pigeonite), magnetite, and sometimes olivine. These minerals play a significant role in the carbon sequestration process. The reactivity of minerals in tholeiitic basalt determines their ability to undergo mineral carbonation reactions with CO₂. Olivine and pyroxene minerals are generally more reactive compared to plagioclase feldspar. Magnetite can also contribute to carbonation reactions but to a lesser extent. The key mineralization reactions that occur during the carbonation process are tabulated in Table 24:

The factors that influence the reactivity of minerals in tholeiitic basalt and, consequently, the efficiency of CO₂ storage are as follows:

Temperature and Pressure: Higher temperatures generally increase the rate of mineral carbonation reactions. Elevated temperatures can enhance the kinetic rates of reactions, promoting the conversion of CO₂ into carbonate minerals. The optimal temperature range for efficient carbonation of minerals in tholeiitic basalts typically falls between 100 and 200 degrees Celsius ^[95][178]. Pressure conditions can impact the stability and reactivity of minerals. High-pressure environments may favor mineral carbonation reactions by promoting closer contact between minerals and CO₂. However, depending upon the geological settings (mid-ocean ridges, continental flood basalts, and rift zones), the carbonation pressure may vary in tholeiitic basalts. In the case of tholeiitic basalts, pressure conditions ranging from atmospheric pressure to a few hundred megapascals (MPa) are commonly encountered ^[96][179].

Dissolution Rate: Tholeiitic basalt contains 40%–70% plagioclase and plagioclase has the highest dissolution rates as depicted in Table 32 compared to Olivine and Pyroxene. Thus, tholeiitic basalt has higher carbonation potential than alkali basalts.

Fluid Composition: The composition of fluids in contact with tholeiitic basalts affects mineral reactivity. Fluids can introduce dissolved CO₂ and other ions that participate in carbonation reactions. The presence of certain ions, such as calcium, magnesium, and iron, can enhance mineral dissolution and precipitation, leading to effective CO₂ storage ^[97][180].

Fluid pH and Redox Conditions: The pH and redox conditions of the fluid significantly impact mineral reactivity. Different minerals have specific pH ranges at which they are more prone to dissolution or precipitation. Tholeiitic basalts generally exhibit slightly acidic to neutral pH conditions (pH 5 to 7) favorable for mineral carbonation. Redox conditions can affect the stability of minerals and their ability to react with CO₂ ^[98][181].

Grain Size and Surface Area: It has dominant percentage of plagioclase. According to Table 32, plagioclase demonstrates high reactivity due to its smaller grain size and larger surface area, making it particularly favorable for carbonation process.

Rock Composition: The specific mineralogical composition of tholeiitic basalt affects its reactivity. Basalts rich in olivine and pyroxene minerals tend to exhibit higher reactivity due to the presence of highly reactive phases. The relative abundance and distribution of these minerals within the tholeiitic basalt can influence the overall carbonation potential ^[99][182].

Geological Setting: The geological setting in which tholeiitic basalt is located can also impact its reactivity for CO₂ storage. Factors such as the availability of fluids, hydrothermal activity, and the presence of other minerals or rock types can influence the effectiveness of mineral carbonation processes ^[99][182].

Considering these factors, CO₂ storage in tholeiitic basalts can be optimized by controlling temperature, pressure, fluid composition, pH, and redox conditions. Proper selection of basaltic rocks with favorable mineralogy and considering the geological setting can enhance the reactivity and carbon storage potential of tholeiitic basalt formations.

CO₂ storage in transition basalts is influenced by the reactivity of its minerals and various factors that affect mineral reactivity. Transition basalts typically contain minerals such as plagioclase feldspar, pyroxene (including augite and pigeonite), olivine, and magnetite. These minerals play a crucial role in the carbon sequestration process. The reactivity of minerals in transition basalts determines their ability to undergo mineral carbonation reactions with CO₂. Olivine and pyroxene minerals are generally more reactive compared to plagioclase feldspar. Magnetite can also contribute to carbonation reactions but to a lesser extent.

The mineralization reactions involved in CO₂ storage in transition basalts include the dissolution of certain minerals and the subsequent precipitation of carbonate minerals. The key mineralization reactions that occur during the carbonation process are tabulated in Table 24. The following factors influence the reactivity of minerals in transition basalts and, consequently, the efficiency of CO₂ storage:

Temperature and Pressure: Higher temperatures generally increase the rate of mineral carbonation reactions. Elevated temperatures enhance the kinetic rates of reactions, promoting the conversion of CO₂ into carbonate minerals. The optimal temperature range for efficient carbonation of minerals in transition basalts typically falls between 100 and 200 degrees Celsius ^[100][183]. Pressure conditions can impact the stability and reactivity of minerals. High-pressure environments may favor mineral carbonation reactions by promoting closer contact between minerals and CO₂. In the case of transition basalts, pressure conditions ranging from atmospheric pressure to a few hundred megapascals (MPa) are commonly encountered ^[101][184].

Dissolution Rate: Transition basalt contains 30%–50% plagioclase and plagioclase has the highest dissolution rates as depicted in Table 32 compared to Olivine and Pyroxene. Thus, these basalts have carbonation potential ranging between alkali and tholeiitic basalts.

Fluid Composition: The composition of fluids in contact with transition basalts affects their mineral reactivity. Fluids can introduce dissolved CO₂ and other ions that participate in carbonation reactions. The presence of certain ions, such as calcium, magnesium, and iron, can enhance mineral dissolution and precipitation, leading to effective CO₂ storage ^[102][185].

Fluid pH and Redox Conditions: The pH and redox conditions of the fluid significantly impact mineral reactivity. Different minerals have specific pH ranges at which they are more prone to dissolution or precipitation. Transition basalts generally exhibit slightly acidic to neutral pH conditions (pH 5 to 7), which are favorable for mineral carbonation. Redox conditions can affect the stability of minerals and their ability to react with CO₂ ^[103][186].

Grain Size and Surface Area: It has a dominant percentage of plagioclase. According to Table 32, plagioclase demonstrates high reactivity due to its smaller grain size and larger surface area, making it particularly favorable for carbonation process.

Rock Composition: The specific mineralogical composition of transition basalts affects their reactivity. Basalts rich in olivine and pyroxene minerals tend to exhibit higher reactivity due to the presence of highly reactive phases. The relative abundance and distribution of these minerals within the transition basalt can influence the overall carbonation potential ^[104][187].

Geological Setting: The geological setting in which transition basalts are located can also impact their reactivity for CO₂ storage. Factors such as the availability of fluids, hydrothermal activity, and the presence of other minerals or rock types can influence the effectiveness of mineral carbonation processes ^[105][188].

The mineralization reactions that occur in high-magnesium basalts (HMB) during CO₂ storage are primarily driven by the reactivity of minerals present in the rock. The major minerals in HMB include olivine, pyroxene (augite and pigeonite), plagioclase feldspar, and magnetite. These minerals undergo chemical transformations as they react with CO₂, leading to the formation of carbonate minerals. The mineralization reactions specific to HMB are tabulated in Table 24. CO₂ storage in high-magnesium basalts (HMB) is influenced by several factors that affect the reactivity of minerals and, subsequently, the efficiency of carbon sequestration. These factors specific to HMB include:

Temperature and Pressure: The temperature range for optimal carbonation in HMB typically falls between 150 to 350 degrees Celsius. Higher temperatures generally enhance the rates of mineral carbonation reactions, facilitating the conversion of CO₂ into carbonate minerals ^[106][189]. Pressure conditions encountered in HMB usually range from atmospheric pressure to a few hundred megapascals (MPa). Pressure can influence mineral stability and enhance the contact between minerals and CO₂, promoting carbonation reactions ^[107][190].

Dissolution Rate: HMB contains dominant percentage of olivine that has lower dissolution rates as depicted in Table 32 compared to Plagioclase and Pyroxene. Thus, HMB will have lower carbonation potential as compared to above-mentioned basalts.

Fluid Composition: The composition of fluids interacting with HMB affects mineral reactivity. Fluids can introduce dissolved CO₂ and other ions that participate in carbonation reactions. Ions such as calcium, magnesium, and iron can enhance mineral dissolution and precipitation, increasing CO₂ storage capacity ^[108][191].

Fluid pH and Redox Conditions: HMB typically exhibits slightly acidic to neutral pH conditions (pH 5 to 7), which are favorable for mineral carbonation. Redox conditions can influence mineral stability and their ability to react with CO₂ ^[109][192].

Grain Size and Surface Area: It has dominant percentage of olivine. According to Table 32, olivine demonstrates moderate reactivity due to its moderate grain size and moderate surface area, making it moderately favorable for carbonation process.

Rock Composition: The mineralogical composition of HMB, with high concentrations of olivine and pyroxene, contributes to its reactivity. Basalts rich in these minerals tend to exhibit higher carbonation potential due to their highly reactive nature ^[110][193].

Geological Setting: The geological setting in which HMB is located can impact its reactivity for CO₂ storage. Factors such as the availability of fluids, hydrothermal activity, and the presence of other minerals or rock types can influence the effectiveness of mineral carbonation processes ^[110][193].

The mineralization reactions that occur in calc-alkaline basalts during CO₂ storage involve the reactivity of specific minerals present in the rock. The major minerals in Calc-alkaline basalts, including plagioclase feldspar, pyroxene (augite and pigeonite), amphibole, and occasionally olivine, undergo chemical transformations as they react with CO₂, resulting in the formation of carbonate minerals. The mineralization reactions specific to calc-alkaline basalts are tabulated in Table 24. These mineralization reactions contribute to the storage of CO₂ in calc-alkaline basalts by converting CO₂ into stable carbonate minerals. The extent of mineral carbonation depends on factors such as temperature, pressure, fluid composition, pH, redox conditions, time, and the specific mineralogy of the rock. By optimizing these conditions, the efficiency of CO₂ storage in calc-alkaline basalts can be improved, offering a promising avenue for carbon sequestration and climate change mitigation.

The minerals commonly found in calc-alkaline basalts include plagioclase feldspar, pyroxene (augite and pigeonite), amphibole, and sometimes olivine. These minerals exhibit different degrees of reactivity and contribute to the carbonation reactions. The specific factors that affect their reactivity and, consequently, CO₂ storage efficiency in calc-alkaline basalts are as follows:

Temperature and Pressure: The temperature range for optimal carbonation in calc-alkaline basalts typically falls between 150 to 350 degrees Celsius. Higher temperatures generally enhance the rates of mineral carbonation reactions, promoting the conversion of CO₂ into carbonate minerals ^[111][194]. Pressure conditions encountered in calc-alkaline basalts usually range from atmospheric pressure to a few hundred megapascals (MPa). Pressure affects mineral stability and influences the availability of fluids and reactants, influencing the carbonation reactions ^[112][195].

Dissolution Rate: Calc-alkaline basalt contains 10%–40% plagioclase, which is relatively low. Though plagioclase higher dissolution rates as depicted in Table 32 compared to olivine and pyroxene, but in context of dissolution rates, its carbonation potential will be the lowest among alkali, tholeiitic, and transition basalts.

Fluid Composition: The composition of fluids interacting with calc-alkaline basalts affects mineral reactivity. Fluids can introduce dissolved CO₂ and other ions that participate in carbonation reactions. The presence of calcium, magnesium, and iron ions can enhance mineral dissolution and precipitation, increasing CO₂ storage capacity ^[113][196].

Fluid pH and Redox Conditions: Calc-alkaline basalts typically exhibit slightly acidic to neutral pH conditions (pH 5 to 7), which favor mineral carbonation. Redox conditions can also influence mineral stability and their ability to react with CO₂ ^[114][197].

Grain Size and Surface Area: It has dominant percentage of plagioclase. According to Table 32, plagioclase demonstrates high reactivity due to its smaller grain size and larger surface area, making it particularly favorable for carbonation process.

Rock Composition: The mineralogical composition of calc-alkaline basalts, with plagioclase feldspar, pyroxene, amphibole, and occasionally olivine, contributes to their reactivity. The proportions and reactivity of these minerals affect the overall carbonation potential of the rock ^[115][198].

Geological Setting: The geological setting in which calc-alkaline basalts are found can influence their reactivity for CO₂ storage. Factors such as the presence of other minerals or rock types, hydrothermal activity, and fluid availability can affect the effectiveness of mineral carbonation processes ^[116][199].

Ocean island basalts (OIBs) have specific mineral compositions that play a vital role in the carbonation process during CO₂ storage. The reactivity of minerals such as plagioclase feldspar, pyroxene, olivine, and occasionally amphibole in OIBs allows them to undergo chemical transformations when exposed to CO₂, resulting in the formation of stable carbonate minerals. These mineralization reactions are crucial for sequestering CO₂ in basalt, offering a potential solution for climate change mitigation.

Temperature and Pressure: Several factors influence the efficiency of carbon sequestration in OIBs. Temperature is a significant factor, as the optimal range for carbonation in OIBs typically falls between 150 to 350 degrees Celsius. Higher temperatures promote faster rates of mineral carbonation reactions, facilitating the conversion of CO₂ into carbonate minerals ^[117][200]. Pressure conditions encountered in OIBs range from atmospheric pressure to a few hundred megapascals (MPa). Pressure affects the stability of minerals and influences the availability of fluids and reactants, thereby impacting the carbonation reactions ^[118][201].

Dissolution Rate: OIB contains olivine (40%–50%) as a dominant mineral that has lower dissolution rates as depicted in Table 32 compared to plagioclase and pyroxene. Thus, OIB will have lower carbonation potential as compared to alkali, tholeiitic, and transition basalt.

Fluid Composition: The composition of fluids interacting with OIBs also influences mineral reactivity. Fluids introduce dissolved CO₂ and other ions that participate in carbonation reactions. Calcium, magnesium, and iron ions, in particular, can enhance mineral dissolution and precipitation, increasing the capacity for CO₂ storage ^[119][202].

pH and Redox Reactions: Fluid pH and redox conditions play a role in OIBs, with slightly acidic to neutral pH conditions (pH 5 to 7) favoring mineral carbonation. Redox conditions can also influence mineral stability and their ability to react with CO₂ ^[120][203].

Grain Size and Surface Area: It has a dominant percentage of olivine. According to Table 32, olivine demonstrates moderate reactivity due to its moderate grain size and moderate surface area, making it moderately favorable for carbonation process.

Rock Composition: The specific mineralogy and proportions of minerals in OIBs impact their reactivity and CO₂ storage potential. Certain minerals, such as olivine, exhibit higher reactivity to carbonation, significantly influencing the overall CO₂ storage capacity ^[121][204].

Geological Setting: The geological setting of ocean island basalts (OIBs) significantly impacts the efficiency of CO₂ storage. Factors such as rock permeability, porosity, fractures, fault networks, water–rock interactions, geological heterogeneity, and depth/pressure conditions influence the availability of reactants, fluid flow, mineral reactivity, and the overall carbon sequestration potential. Understanding and characterizing these geological aspects are crucial for optimizing CO₂ storage strategies in OIBs and ensuring long-term stability ^[121][204].

CO₂ storage in island arc basalts (IAB) involves the reactivity of its minerals and is influenced by various factors that affect the efficiency of carbon sequestration. Island arc basalts are formed in subduction zones where oceanic plates are being subducted beneath continental plates, leading to the formation of volcanic arcs. The mineralogy and specific characteristics of island arc basalts influence their potential for CO₂ storage.

The mineralization reactions involved in CO₂ storage in island arc basalts (IAB) primarily depend on the reactivity of the minerals present in the rock. The specific reactions can vary based on the mineralogy and composition of the basalts. However, Table 24 contains general mineralization reactions that may occur during CO₂ storage in island arc basalts:

Temperature and Pressure: The temperature range for optimal carbonation in island arc basalts varies, typically ranging from 200 to 500 degrees Celsius. Higher temperatures enhance the rate of mineral carbonation reactions ^[122][205]. Island arc basalts experience moderate- to high-pressure conditions due to the subduction process. The pressure range encountered can vary from several hundred megapascals (MPa) to gigapascals (GPa). Pressure affects mineral stability and the availability of reactants, impacting carbonation reactions ^[123][206].

Dissolution Rate: OIB has high percentage of plagioclase (30%–60%) that has the highest dissolution rates as depicted in Table 32 compared to Olivine and Pyroxene. Thus, OIB will have lower carbonation potential as compared to above-mentioned basalts but lower than tholeiitic basalt in context of dissolution rates.

Fluid Composition: The composition of fluids interacting with island arc basalts influences mineral reactivity and carbonation processes. The presence of water-rich fluids with dissolved CO₂ and other ions enhances mineral dissolution and precipitation, facilitating carbon storage ^[124][207].

Fluid pH and Redox Conditions: Island arc basalts typically experience slightly acidic to neutral pH conditions (pH 5 to 7), which can promote mineral carbonation. Redox conditions, including the presence of oxidizing or reducing agents, influence mineral stability and reactivity ^[125][208].

Grain Size and Surface Area: It has dominant percentage of plagioclase. According to Table 32, plagioclase demonstrates high reactivity due to its smaller grain size and larger surface area, making it particularly favorable for carbonation process.

Rock Composition: The specific mineralogy and proportions of minerals in island arc basalts affect their reactivity and carbonation potential. The presence of reactive minerals, such as olivine or pyroxene, can significantly contribute to CO₂ storage ^[126][209].

Considering the mineralogy of island arc basalts and optimizing temperature, pressure, fluid composition, pH, redox conditions, time, and rock composition, the efficiency of CO₂ storage can be enhanced. Carbonation reactions convert CO₂ into stable carbonate minerals, effectively sequestering CO₂ from the atmosphere. Island arc basalts provide a potential reservoir for CO₂ storage, contributing to climate change mitigation efforts.

A summary of the above discussion related to the parameters affecting reactivity of basalt for its carbonation potential is given in Table 45.