This chapter illustrates how sand and silicate extraction systems work, how they interact with each other and how they connect to mid- and downstream sectors. An analysis of international sand and silicate trade shows that the bulk of these materials is consumed locally. Overlapping production systems involving artisanal and small-scale as well as industrial mining operations lead to the blending of feedstocks, especially in local contexts. Some sand and silicate materials are traded internationally as often overlooked inputs in global supply chains. Despite the importance of locally contained production and trade systems in the sector, considering the sheer scale of their consumption, international trade in sand and silicates is significant.
Due Diligence for Responsible Sand and Silicate Supply Chains
Abstract
Developing an understanding of the structure and dynamics of sand and silicate supply chains is important for enabling scoping and risk identification and for developing appropriate measures to mitigate risks and address impacts. A key feature of sand and silicates is the heterogeneity of supply chain operators with the presence of few dominant players (Torres et al., 2021[32]; Holm, Gallagher and Franks, 2023[33]). This stems from the existence of diverse resource production systems involving many types of minerals, extraction practices, supply chains, governance structures and actors.
Figure provides an overview of sand and silicate supply chains from extraction to processing, transport, and end-use industries, as well as recycling. Some supply chains are short and straightforward, such as the local supply of construction aggregates, while others are longer and more complex, involving international trade and industrial transformation. This diagram, while schematic and simplified, provides a foundation for exploring the complexities and opportunities for risk mitigation within these supply chains.
A key point critical to understanding the risk landscape of sand and silicate supply chains is that, in contrast to many other minerals, sand and silicates are extracted from two types of sourcing environments: dynamic and static. In dynamic systems, sand, gravel and clay play important ecological functions that can be significantly impacted by their removal. Dynamic systems include freshwater systems whereby river currents shape, transport and deposit rocks and sediments in river channels, lakes, wetlands and estuaries, as well as marine systems where marine processes like erosion and deposition shape distinct silicate deposits on the seabed and along coastlines. While being shaped by water and rivers, sand and silicates are themselves essential to the functioning of freshwater and marine systems with aquatic life. Sand and silicates help maintain a balanced natural sediment structure and enable nutrient cycling on which aquatic life depends. Marine sand extraction from coastal ecosystems is estimated to account for 4-8 billion tonnes of sand and silicate consumption each year (UNEP, 2024[34]).
In static systems sand, gravel, clay and crushed stone are not typically fundamental to the functioning of the ecosystems above them, but extraction can still disturb these ecosystems. Static systems include terrestrial systems such as rocks, stones, sand, gravel, or other silicate materials which are typically extracted from the earth's surface in open pit mines or quarries and can result from industrial processes applied in manufacturing systems. A significant share of naturally sourced sand and silicates undergoes mechanical or manual processing within manufacturing systems, which are becoming increasingly important in global sand and silicate production (Bhatawdekar et al., 2021[35]). Most manufacturing systems transform natural materials like stones and quartz for uses further downstream. This transformation and processing comprise a multitude of steps which can result in a diverse range of subsequent material flows. Due to the complexity and variety of processing techniques, manufacturing systems are generally seen as a distinct source of supply in the sector1. An analogy to scrap and secondary sourcing in other mineral supply chains can be made where such materials tend to be treated as a distinct source of supply separate from primary or mined materials for due diligence purposes, even if the comparison with manufacturing systems of sand and silicates is not an exact equivalent.
Each of the four extraction systems – from freshwater, marine, terrestrial and manufacturing systems, produces sand and silicates with unique characteristics suited to different applications, yet they all share similar mineralogy. Importantly, sand and silicate extraction can also take place in areas where extraction systems co-exist (see Figure 2.2). For example, quarrying can take place in marine systems, through coastal quarrying, as well as in terrestrial systems by means of natural stone quarrying. Sand and silicates can also be engineered through manufacturing processes, sourced as secondary materials or recycled from non-sand mineral extraction which generate sand in the form of tailings. While material recycling and secondary sourcing does exist in the supply chain, the characteristics of secondary sand and silicate sourcing and related risks and impacts fall beyond the scope of this report.
The scale of extraction from artisanal to small-scale and industrial operations
Sand and silicates are extracted through a wide range of methods, from artisanal to large-scale and highly mechanised operations. Artisanal and small-scale mining (ASM) plays a crucial role in producing sands, clays, and stones used in construction in Asia, Africa and Latin America. In Sub-Saharan Africa, 90% of all sand mining is estimated to originate from ASM2 which is broadly characterised by low levels of mechanisation. Extraction and initial processing support the livelihoods of millions of artisanal miners and their dependents. The artisanal production of industrial sands, albeit rare, also exists. Small to medium-sized enterprises (SMEs) and local businesses are equally important actors in sand and silicate supply chains. They tend to operate in local markets of sand and silicates or in the production of niche applications. Hydraulic pumping, mechanical excavators, and transporters can be used in small-scale operations. In the United States, in 2023, more than three thousand SMEs were observed to produce sand and silicates across all 50 States (USGS, 2024[36]). Large-scale mining (LSM) and quarrying enterprises are present in sand and silicate supply chains but, compared to other commodities, are less dominant. Sandstone, quartzite, basalt or other silica-rich materials can be extracted from large, formal quarries where capital-intensive, industrial operators engage in mining and preliminary processing at larger scale (MPA, n.d.[37])]). Similarly, industrial extraction can dominate in marine dredging and excavation as it requires relatively sophisticated equipment to remove sediment from the seabed (IADC, 2023[27]). LSM operations can also exist alongside informal and poorly regulated extraction activities (see Box 2.1).
ASM in sand and silicates often involves a higher proportion of local community members, including Indigenous People and supports the livelihoods of millions of people, as recognised in the 2018 Mosi-oa-Tunya Declaration on Artisanal and Small-scale Mining, Quarrying and Development, but there is limited analysis of the extent of artisanal sand extraction and trade. For example, in Morocco, aggregate quarries account for a measurable share of GDP due to their important role in the national construction sector. The artisanal production of construction aggregates is also a major source of local livelihoods and an important driver for local economic development in Southeast Asia. The large volumes extracted and the physical footprint of the sector, however, can disrupt economic activities and livelihoods that rely on the same ecosystems, a challenge made more pronounced by the unsustainable rates of removal of sand and silicates. For example, millions of people depend on the Mekong River for fisheries and agriculture. But these sectors that are put at risk by unsustainable levels of extraction with 35-55 million m3 of sand being extracted each year exceeding replenishment rates by a factor of ten. The effects can involve significant health and environmental risks. Livelihoods of artisanal sand miners also tend to be threatened by the entry of more mechanised operations, for example in Colombia.
Sources: Agharroud et al. (2023[38]), Assessment of the sustainability of aggregate quarrying practices in northern Morocco: A case regarding the eastern provinces of the Tangier Peninsula, https://doi.org/10.1007/s10064-023-03252-x; Asare, Dawson and Hemmler (2023.[39]), A sand-security nexus: Insights from peri-urban Accra, Ghana, https://doi.org/10.1016/j.exis.2023.101322; Marschke and Rousseau (2022[40]), Sand ecologies, livelihoods and governance in Asia: A systematic scoping review, https://doi.org/10.1016/j.resourpol.2022.102671; Asif and Van Arragon (2023[41]), Precarious livelihoods at the intersection of fishing and sand mining in Cambodia, https://doi.org/10.1007/s13280-023-01963-9; WWF (2023[42]), SUMMARY REPORT: Sand Budget for Viet Nam Mekong Delta, https://www.sandbudget.net/the-viet-nam-mekong-delta-sand-budget.
Sand and silicates are extracted in different geographies, including in high-risk areas
Due to the ubiquity of sand and silicates, most conflict-affected and high-risk areas (CAHRAs)3 will have some relationship to sand and silicates which can interact with conflict in different ways. As with all other mining, the co-existence of artisanal with more mechanised mining operations can involve resource competition and fuel tensions in mining communities (see Box 2.1). The impacts of sand and silicate extraction on the availability and quality of natural resources such as clean water can also exacerbate community tensions leading to conflict (Bisht and Gerber, 2017[43]). As with any other RBC risk or impact, local tensions and community conflict in mining regions can materialise over time into sustained social unrest and opposition causing temporary suspension of mineral production or definite mine closure (OECD, 2023[44]). Inter-state conflict emergence and related state-imposed economic sanctions can, as in the case for Ukraine and the Russian Federation, demand exit by sand and silicate companies from specific markets or supply chains4. Conflict over sand and silicate resources can further emerge in the context of geo-political competition. Gravel, for example, has become a source of political and economic interest because of its use for climate-change adaptation measures. Where natural sand, earth and ice are eroding due to the effects of climate change, gravel and sand are used to replenish coasts and ice roads, as for example in the Arctic (Bendixen et al., 2019[45]; Bennett, 2023[46]). Sand and silicates also play an essential role in post-conflict and post-disaster reconstruction (Rogers, 2023[47]; Oxford Economics, 2023[48]). OECD standards on responsible business conduct recommend enhanced due diligence by companies when they source mineral materials from countries or transit hubs with specific location or supplier characteristics. Sourcing decisions involving CAHRAs or countries with known export-to-production discrepancies or suppliers that are connected to CAHRAs should trigger enhanced due diligence (see Section 3).
Interconnected supply chains
Significant overlap exists in where and how sand and silicate materials are produced. Sand and silicates can enter a variety of supply chains while originating from the same sources as is illustrated in Figure 2.3. Sand, gravel and stone are materials that can originate from all four extraction systems, including marine systems. Conversely, clays are predominantly produced in freshwater and terrestrial systems. Overall, terrestrial, manufacturing and freshwater systems are used to produce almost all types of sand and silicates while marine systems feed into sand, gravel and stone supply chains only. Sand and silicates that come from distinct deposits and locations can ultimately be blended when travelling down the supply chain. For example, sand and gravel production can be aggregated locally and traded in bulk to nearby larger firms, sometimes subject to further grading, cleaning, shaping and sizing (UNDP, 2019[49]). Aggregates extracted by a range of different actors from artisanal, small-scale and industrial sectors can ultimately find their way into local, national or international supply chains, for example for construction projects (Da and Le Billon, 2022[50]).
Complex sourcing and blending can result in materials linked to serious risks entering global supply chains, as outlined in Box 2.2. Governance challenges are widely discussed for aggregate production and trade, considering the scale of extraction of gravel, sand and stone, as well as the predominance of local, often informal, production and consumption circuits. However, similar governance challenges can characterise extraction and trade of other types of sand and silicate materials. 3 provides more contextual information.
Available data and statistics on international trade of sand and silicate materials are limited. In some cases, countries apply Harmonised System (HS) classifications to the import and export of different types of sand and silicates. For example, data for high-purity quartz is included in the Harmonised Tariff Schedule of the United States (HTS) but mixed with other types of sand and quartz which renders the tracking of these materials difficult (USGS, 2024[18]). Given available information, experts estimate that 1-2% of sand, gravel and quartz consumed worldwide by volume are traded internationally (Torres et al., 2021[32]). Despite the importance of local sourcing in these low-value supply chains, sand and silicate materials are traded internationally at significantly higher volumes than many other high-value minerals. Eight major industries are closely linked to the sand and silicates sector – construction, automotive, electronics, ceramics, glass, solar energy, oil and gas, and abrasives. However, the importance of sand and silicates as inputs for products or industrial processes is often overlooked. The sand and silicates market is estimated to amount to USD 600 billion annually in value, making the sector more than 50% larger than the value of annual mined gold production while being more than a million times larger in volume.
Sand and silicate extraction is often poorly regulated with little oversight by government agencies, making informality common. Legal frameworks often do not assign responsibility for regulating the sector, either at national or sub-national levels. In some regions, the existence of dual systems of formal and informal extraction involving industrial and smaller-scale or artisanal operators can pose additional governance challenges. Weak enforcement mechanisms, coupled with soaring demand for construction materials and industrial minerals, can undermine attempts to regulate informal mining, and attempts to do so are further complicated by a lack of comprehensive data on extraction rates, trade, and consumption.
Aggregates are typically sourced from coastal areas, riverbeds, and terrestrial quarries. Formal extraction is regulated in some places, though enforcement challenges remain in many jurisdictions. Meanwhile, informal extraction - particularly from beaches - has raised environmental concerns, including significant coastal erosion and loss of natural habitats. While riverbed and quarry extraction tend to be more regulated, informal mining activities persist. The complexity of these supply chains, coupled with high demand, continues to drive both formal and informal trade in construction aggregates.
While most domestically extracted aggregates are consumed by nearby urban centres, international trade in sand and gravel does exist and concerns have been raised about informal construction sand and gravel trade across borders in regions like North and sub-Saharan Africa, and Southern Europe.
Source: UNEP (2019[2]), Sand and sustainability: Finding new solutions for environmental governance of global sand resources, https://unepgrid.ch/storage/app/media/documents/Sand_and_sustainability_UNEP_2019.pdf; Padmalal and Maya (Padmalal and Maya, 2014[24]), Sand Mining: Environmental Impacts and Selected Case Studies, https://link.springer.com/book/10.1007/978-94-017-9144-1; Pilkey et al. (2022[51]), Vanishing sands: Losing beaches to mining, https://doi.org/10.1215/9781478023432; Abderrahmane (2022[52]), Extracting and Trafficking Morocco’s Coastal Sand, https://enactafrica.org/research/research-papers/extracting-and-trafficking-moroccos-coastal-sand; Ameziane and Suykens (2023[53]), Political Settlements and the Historical Development of Sand Governance in Morocco, https://doi.org/10.1016/j.exis.2023.101245.
Sand, gravel and stones are sourced, often locally, in extraordinary volumes for construction
Construction – or the built environment - is the largest sand and silicates consuming sector. Annually, 30 billion tonnes of sand, gravel and rocks are consumed for residential and non-residential construction, infrastructure including roads, airports, ports, and railways, and artificial islands and land reclamations projects. Natural sand of all kinds as well as natural stone, gravel, rocks, other aggregates as well as limestone and clay are all used to produce concrete, bricks, cement, float glass and other inputs to the built environment. Representing approximately 13% of global GDP (World Economic Forum, 2025[54]), the construction sector accounts for by far the largest volume of sand and silicate materials use and is a main driver of global demand (UNEP, 2024[55]). The global demand for buildings and infrastructure in the last thirty years has led to a fourfold increase in concrete production, reaching approximately 26 gigatonnes per year by 2020. The yearly need for virgin concrete aggregates recently surpassed the extraction of all fossil fuels in terms of annual extraction volumes (Watari et al., 2023[56]).
Sources: UNEP (2019[2]), Sand and sustainability: Finding new solutions for environmental governance of global sand resources, https://unepgrid.ch/storage/app/media/documents/Sand_and_sustainability_UNEP_2019.pdf; Research and Markets (2024[20]), Natural Stone Global Market Report 2024, https://www.researchandmarkets.com/reports/5766803/natural-stone-global-market-report; USGS (2024[36]), Mineral Commodity Summaries 2024 SAND AND GRAVEL (CONSTRUCTION), https://pubs.usgs.gov/periodicals/mcs2024/mcs2024-sand-gravel.pdf; OEC (2022[57]), Sand, https://oec.world/en/profile/hs/sand; OEC (OEC - Stone, sand and gravel, 2018[58]), Stone, sand and gravel, https://oec.world/en/profile/sitc/stone-sand-and-gravel.
Sand and silicates for the construction sector often come from local sources and are used without crossing any borders. For example, in 2023, an estimated 920 million tonnes of construction sand and gravel were produced and consumed in the United States (USGS, 2024[36]). However, access, affordability and governance challenges have led to a growing trend of countries importing sand and silicates to meet their construction needs. For example, Pacific islands host a limited range of geological materials and rely on long-distance intra-regional trade in aggregates. Even where there are abundant resources, the necessary infrastructure and capacity to extract these resources may be limited. With demand outstripping local production capacity, more countries are resorting to sand and silicate imports. The fastest growing import markets in gravel and crushed stone for Pacific countries are the People’s Republic of China (China), New Zealand and Japan (Rogers, 2023[47]). In 2022, China was the largest importer of construction sand, while the United States was the largest exporter for the same year (see Figure 2.4).
Quartz and silicon: critical raw materials for semiconductors and solar energy
Sand and silicates comprise the raw materials for semiconductors and solar panels, in addition to the crucibles used to manufacture silicon wafers for these products. This starts with quartz, in the form of gravel from riverbeds or rock extracted from the earth, which is used to produce metallurgical silicon (MG-Si) or silicon metal. Quartz is one of the most common materials in the world and available in many regions (Kalyani Mohanty, 2025[59]), but deposits vary in purity and strength. A purity of 99.4%-99.8% silicon dioxide (SiO2) is needed for quartz used in silicon metal production. In addition, quartz feeding into silicon metal production needs to be sufficiently heat-resistant during smelting. Geological sources of quartz suitable for silicon metal production can be found across all five continents, pointing to a relatively high level of diversification at the raw material production stage. However, significant bottlenecks emerge when moving down the supply chain.
Following quartz extraction and processing into silicon metal, the metal is used to produce polycrystalline silicon rods or polysilicon. Polysilicon can be produced at different grades of Si content, but very high purities can be used for the manufacturing of semiconductor ingots and wafers, at 99.999999999% (11 nines, or 11 N) while polysilicon used in the solar industry is of a lesser grade, requiring purity of 9-10N, though this gap is closing due to recent technological shifts in the solar industry requiring higher purity (Bernreuter, 2025[60]). Figure 2.5 provides an overview of how quartz is transformed into silicon metal and polysilicon for the purpose of silicon wafer manufacturing in both solar and semiconductor supply chains.
Over the past twenty years, China has achieved dominance over global polysilicon production by expanding its market share from negligible production in 2005 to almost 95% of global production in 2025, of which around 98% is solar-grade polysilicon with a purity of 9 to 10N (Bernreuter, 2025[60]). One further step down the solar supply chain, China is also the leading solar-grade silicon ingots and wafer producer with a global market share of 95% and 97% respectively (IEA, 2022[61]; Bernreuter, 2019[62]). China has also become the leading global supplier of silicon metal, accounting for around 4.9 million metric tonnes or 85% global production of this material in 2024 (Shangai Metals Market, 2025[63]; CRU Group, 2025[64]). OECD countries like France, Norway and the United States, in addition to Brazil, are estimated to account for most of the remainder (Kalyani Mohanty, 2025[59]; BRGM, n.d.[65]). China is not only responsible for most of the world’s global silicon metal output, but it also consumes approximately two thirds of this material to feed its domestic solar industry among other sectors in the country.
In response to dependency on China, some OECD countries have listed silicon metal as a critical material, particularly due to its use in the semiconductor industry (Australia, the United States, United Kingdom, Japan, Korea, the European Union). However, despite China’s dominant role overall in silicon, solar-grade polysilicon, ingots and wafers, only a handful of companies, all of which are based in OECD countries, possess the technology and know-how to produce semiconductor-grade polysilicon with a purity of 11N. Germany and the United States are leading producers and account for approximately 65% of global market share while Japan and Korea also have significant semiconductor-grade polysilicon production capacities (Bernreuter, 2025[60]). By comparison, China’s market share of semi-conductor grade polysilicon is estimated at less than 10% (Bernreuter, 2025[60]). OECD countries also dominate the semiconductor-grade silicon wafer market, which is again heavily concentrated. The largest semiconductor-grade silicon wafer producers are Germany, Japan, Korea, the United States, and Chinese Taipei, accounting together for around 85% of the global semiconductor-grade wafer market ((SIA), 2025[66]).
Sources: SIA (2025[66]), Notice of Request for Public Comments on Section 232 National Security Investigation, https://www.semiconductors.org/wp-content/uploads/2025/08/Semiconductor-Industry-Association-SIA-Comments-Polysilicon-Section-232-Investigation.pdf; Bernreuter (Bernreuter, 2025[60]), The Polysilicon Market Outlook 2029, https://www.bernreuter.com/polysilicon/industry-reports/polysilicon-market-outlook-2029/; Bernreuter (2019[62]), Bernreuter Research, https://www.bernreuter.com/solar-industry/value-chain/; Shanghai Metals Market (2025[63]), https://zhuanlan.zhihu.com/p/20308202564; Jennings (2023[67]), A review of high-purity quartz for silicon production in Australia, https://doi.org/10.1080/08120099.2024.2362296; USGS (2024[18]), Mineral Commodity Summaries 2024, https://pubs.usgs.gov/periodicals/mcs2024/mcs2024-quartz.pdf; Kalyani Mohanty (2025[59]), Perspectives for High-Purity Quartz from European Resources, https://doi.org/10.3390/min15101080; Yameng Ma (2025[68]), Characteristics of high-purity quartz raw materials for crucibles and exploration of key purification technologies, https://doi.org/10.1016/j.mineng.2025.109446; OECD (2025[69]), Mapping the Semiconductor Value Chain, https://www.oecd.org/content/dam/oecd/en/publications/reports/2025/06/mapping-the-semiconductor-value-chain_5ba52971/4154cdbf-en.pdf.
The interdependencies in the semiconductor value chain extend beyond China’s dominance in silicon metal and OECD countries’ leading roles in semiconductor-grade polysilicon and wafers. The small share of semiconductor-grade polysilicon of the global total, only 2.4% compared to the solar-grade polysilicon market share of 97%, will have implications for the resilience and economic sustainability of semiconductor-grade producers operating in OECD countries ((SIA), 2025[66]). To reach viable economies of scale, semiconductor-grade polysilicon producers tend to produce higher volumes of solar-grade polysilicon for which the market is larger and production costs are lower. The implication of this is that both markets are interconnected and operators involved in semiconductor-grade polysilicon production will not be immune to global price and industry trends in the solar sector ((SIA), 2025[66]).
Another dimension of the semiconductor value chain in which OECD countries excel is raw materials that, instead of being inputs for semiconductors or solar panels, are critical to manufacturing processes. Crucibles derived from high-purity quartz (HPQ) with a purity of at least 5N are tubes resistant to liquid silicon which are commonly used to grow monocrystalline silicon ingots and ultimately produce wafers5. Using the Czochralski process, polysilicon is melted in HPQ-crucibles at very high temperatures to produce monocrystalline silicon or monosilicon ingots. This method is commonly used for both solar and semiconductor ingot manufacturing and has expanded in recent years, being critical to nearly all semiconductor manufacturing.
HPQ demand has increased in response and is estimated to increase 40-fold by 2050 (Geoscience Australia, 2024[70]; Gabriela Kazimiera Warden, 2023[71]). China consumes 60% of global HPQ production. However, in contrast to lower-purity quartz, natural HPQ deposits are rare (Kalyani Mohanty, 2025[59]) and mined production is heavily concentrated in the United States. A single US mine is estimated to account for about 70% of global supply (Kalyani Mohanty, 2025[59]; Geoscience Australia, 2024[70]; Yameng Ma, 2025[68]) and few viable HPQ deposits are known to exist in other countries (USGS, 2024[18]). This level of concentration had disruptive effects on the supply chain in 2024 due to Hurricane Helene leading to a temporary suspension of production at the US mine (The Quartz Corp, 2024[72]). Some companies have started to manufacture HPQ from low-quality quartz through purification, but this method has not proven economically viable enough to scale up (USGS, 2024[18]).
China, while having achieved market dominance in many other critical mineral supply chains, is dependent on HPQ imports from the United States to feed domestic crucible production. To reduce import dependence, China has listed HPQ as a strategic material and national exploration efforts have started to bear fruit, resulting in the recent discovery of HPQ reserves in the country (Hart, 2025[73]). As in any supply chain, exploration and mine development can contribute to changing supply chain dependencies over time. While lead times from mineral discovery to production tend to vary by mineral, location and mine type, historic analysis shows that it takes on average 16 years to bring greenfield mines online (IEA, 2021[74]). China has also responded to bottlenecks in the semiconductor market through heavy investment in the production of higher-grade silicon wafers (Allen, 2023[75]).
Overall, the case of quartz and silicon use in solar and semiconductor supply chains illustrates how supply chain dependencies can take multiple forms and shift direction several times when moving down the supply chain or into strategically connected sectors, revealing both significant vulnerabilities and advantageous positions in the sector for OECD countries (see Figure 2.5). In a context of growing economic security concerns, this strategic supply chain is an example of interdependency, which can inform efforts by policy makers to enhance resilience. While trade dependencies in the silicon metal and downstream solar and semiconductor markets have received strong attention by policy makers in recent years, the raw materials required for polysilicon and monocrystal ingot production, HPQ, have received less attention despite the rest of the value chain depending on it.
Sand and silicates are indispensable but often hidden inputs in many industries and sectors
Silicon is only one intermediary product made from sand and silicates feeding into various mid-stream and downstream sectors. Approximately 40 million tonnes of sand-based glass are produced annually (Glass Alliance Europe, n.d.[76]) feeding into electronics, automotives, infrastructure and other sectors. Speciality glass, itself derived from silicon, can feed into semiconductor manufacturing as well as medical and other equipment and can also include other types of speciality glass such as borosilicate glass for laboratory use and fibre optic glass for light signal transmission. The most common type of industrial glass, float glass, is used for windows, mirrors, drinking glasses, glass packaging and decorative glassware. Sheet glass, thinner and lower cost, is used in residential windows and picture frames. Safety glass includes tempered glass, heat-treated for strength and resistance, and laminated glass, maintaining cohesion when shattered. Smartphones, which were the world’s ninth most traded product in 2022 (OEC, 2022[77]) also use glass that is made from silica, which is sourced from industrial operations in Europe, the United States, China and other countries in Southeast Asia. The case of smartphones illustrates how sand and silicate use can sometimes be obscured by higher-profile materials in global mineral supply chains.
In the automotive sector, silica sand is not only a key ingredient in the production of safety glass used for windscreens and windows of vehicles. It is also used in the production of tyres to improve traction and performance while silica-based materials are essential in manufacturing vehicle composites, used in electronics systems, utilised in paints and coatings, and essential inputs for glass fibres woven into glass fibre fabrics which are utilised in automotives as well as electronics and others. Sand casting is further used to form various metal parts of a vehicle.
Beyond renewable energy technologies, other types of energy production processes make extensive use of sand and silicate materials. For example, hydropower dams are constructed across rivers or streams to store or divert water for energy production. While sand and silicates (such as silica sand) are not used to hold back and control water directly, they are used as construction materials, primarily as aggregates in concrete and other structural components of hydropower dams. Silica sand is further used in the role of proppant, which is used for fracturing in geothermal development and sand batteries are being explored as a larger-scale solution for storing thermal energy from wind and solar technologies since high-silicon anode material can increase the energy density of batteries. In the oil and gas sector, silica sand contributes to hydraulic fracturing, where it is injected with water and chemicals into rock formations at high pressure, allowing oil and gas to flow more freely.
Tourism and leisure are additional sectors with high dependence on sand and silicate supply. As just one example of tourism’s dependence on sand, coastal and marine tourism accounts for roughly 50% of global tourism or 5.2% of the global GDP. This sector is particularly crucial for the economies of small islands and coastal communities (Northrop et al., 2022[78]). Sand is a major component of building and maintaining golf courses and integral to equestrian sport. Equestrian arenas predominantly use sand as a footing material, with silica sand enhancing shock absorption and stability (Zorn, 2018[79]).
Sand and silicates are additional key ingredients in home- and sanitaryware. Concrete or engineered quartz made from lower-grade natural quartz are used for equipping kitchens while silicate ceramics are commonly used for flooring and equipping interior spaces. Porcelain, made from kaolin clay and feldspar, is a type of ceramic widely used while ceramic toilets and sinks made from silicate-based clay. In cosmetics, sand and silicates like mica and talc are commonly used while hydrated silica acts as a powerful abrasive in toothpaste.
Ultimately, sand and silicates contribute to various components and manufacturing processes. Metal processing, including smelting and refining processes, rely on sand and silicates such as high-quality silica. Here again, HPQ is processed into silicon metal which helps to remove unwanted oxygen during steel production. Water filtration, where layers of sand are used to capture suspended solids, sediment, and contaminants as water passes through, is widely implemented in various sectors.
A range of consumer products and services cannot be manufactured without the supply of sand and silicates which serve as critical - and often hidden inputs - in a panoply of industrial processes and sectors spanning automotives, electronics, food and beverages, textiles, medical equipment, cosmetics, homeware and many more. Annex B provides an exhaustive list of applications.
The following points are critical for understanding the structure of sand and silicate supply chains, their functioning and the underlying dynamics of consumption and production:
Sand and silicates are extracted from both dynamic and static sourcing environments. In dynamic systems, sand, gravel and clay play important roles in the functioning of ecosystems which can be significantly impacted by their removal, notably when volume and pace of extraction exceeds sustainable thresholds or their rate of replenishment.
As sand and silicates are extracted across the globe through artisanal, small-scale or industrial operations, most sand and silicate production and trade processes will in some way relate to CAHRAs.
Sand and silicate supply chains can have mixed and overlapping sources for material flows that feed a wide range of applications and downstream uses. Their interconnectedness, and sometimes deep integration in international supply chains, can render these materials - and their associated risks - invisible.
Sand and silicates can serve as critical materials in supply chains of strategic importance to electronics, renewable energy and automotives.
Important but widely overlooked upstream segments of some sand and silicate supply chains are concentrated in OECD countries with the United States emerging as a dominant supplier of construction sand and high-purity quartz used in semiconductor manufacturing.
← 1. One example is manufactured sand which is fine aggregate produced by crushing and shaping rock, then screening, cleaning, and blending the resulting fractions to achieve a consistent, specification-grade sand for construction use (Cement Concrete & Aggregates Australia, 2008[202])
← 2. Gankhuang, U. (22 May 2024) Plenary panel intervention, ACP-EU Development Minerals Programme, implemented by UNDP: https://www.developmentminerals.org/index.php/en/ Responsible Sand and Silicates: Implications for Due Diligence. This figure was estimated by participants in the ACP-EU Development Minerals Programme country programmes. ASM participation in supply chains is difficult to validate.
← 3. CAHRAs are defined by the presence of armed conflict, violence or other risks of harm to people. This includes high-risk areas prone to political instability, institutional weakness, insecurity, collapse in civil infrastructure and widespread violence, available at: (OECD, 2018[82])
← 4. Roca Group and Holcim: experiences related to the emergence of the Ukraine war in 2022.
← 5. Multi- instead of monocrystalline silicon ingots used to be commonly used for solar-grade silicon wafer production. However, the share of multicrystalline ingots in the solar industry has gone down from 74% in 2016 to to zero percent in 2024. Using the Czochralski process which relies on these HPQ-derived crucibles, monocrystalline silicon ingots are nowadays the preferred input for both semiconductor and solar-grade silicon wafer production while purity requirements differ ((n.a.), 2025[203])