GypsumEdit

Gypsum is a soft, widely distributed mineral that plays a fundamental role in modern construction, agriculture, and manufacturing. Chemically, it is calcium sulfate dihydrate (CaSO4·2H2O), and in its pure form it ranges from white to colorless, though impurities can yield gray, yellow, or brown hues. As an evaporite mineral, gypsum forms when seawater or saline lake waters evaporate and concentrate dissolved minerals, a process that concentrates the mineral in layered deposits around the world. Its abundance and ease of processing have made it one of the most important industrial minerals, supporting everything from housing to food and health. The mineral is harvested from natural beds and, in some places, recovered as a byproduct of other mining operations; it is also produced synthetically in some industrial settings. For more on the broader mineral category and its formation, see Mineral and Evaporite.

Gypsum sits at the intersection of natural resource economics and practical, broad-based industries. It is a cornerstone of modern building materials—most prominently in plaster and drywall—and also contributes to soil health and agricultural productivity when used as a soil conditioner and calcium and sulfur source. As such, its availability, price, and the rules governing its extraction and processing have tangible effects on construction costs, housing supply, and rural economies. See Plaster and Drywall for its common building applications, and Agriculture and Soil for its agricultural uses.

Occurrence and formation

Gypsum occurs in a range of sedimentary contexts, but its most economically important forms are in thick beds laid down by evaporating bodies of water in arid to semi-arid environments. These deposits can be mined in open pits or quarried in areas where the mineral lies near the surface. The mineral readily dehydrates when heated, and this property underpins several industrial products.

In the laboratory and in the field, gypsum is distinguished from related minerals by its softness (on the Mohs scale it is about a 2) and a high solubility in water under certain conditions. If heated to remove part of its water of crystallization, gypsum converts to plaster of Paris (CaSO4·0.5H2O), a material with a long history in sculpture, medicine, and construction. The related mineral anhydrite (CaSO4) is gypsum’s anhydrous form, which can transform back to gypsum under appropriate moisture conditions. See Mohs scale and Calcium sulfate for related properties and chemistry.

Physical properties and classification

Gypsum’s defining feature is its hydrated calcium sulfate structure, which accounts for its relatively low hardness and its high solubility in hot water. Its crystals can occur as tabular plates, fine fibrous masses, or massive beds, often with a pearly to silky luster in exposed surfaces. The mineral’s physical behavior—especially its softness and ability to form quite large crystals—has made it a preferred material in decorative plastering, as well as in industrial processes that require a reliable, inert filler. For a broader sense of how gypsums and related minerals fit into geological classification, see Mineral and Sedimentary rock.

Extraction, processing, and production

Extraction methods are typically straightforward open-pit operations when gypsum is near the surface, with deeper deposits mined by conventional underground techniques where economics justify it. After extraction, ore is crushed and processed to remove impurities, and large volumes of gypsum are stockpiled for shipping to processing facilities. Heating gypsum to drive off part of its water of crystallization yields plaster of Paris, a material with numerous uses in construction, art, and medicine. See Mining and Open-pit mining for general mining practices, and Calcination for the processing step that produces plaster.

Quality control is important in ensuring that the gypsum meets the specifications required for plastering compounds and drywall manufacturing. Impurities can affect setting time and strength, so processing facilities invest in screening, grinding, and sometimes flotation steps to maintain product consistency. For the broader context of industrial minerals and their processing, see Industrial minerals and Processing.

Uses and applications

Construction and building materials: Gypsum is most famously used to make plaster and drywall (gypsum board). Plaster of Paris is used for casts, molding, and decorative work, and gypsum additives help improve workability and fire resistance in some cement and plaster products. See Plaster of Paris and Drywall.
Agriculture and soil management: Gypsum supplies calcium and sulfur to soils and can improve soil structure, especially in soils prone to compaction. It is used as a soil conditioner in many regions with saline or sodic soils. See Agriculture and Soil.
Industry and specialty uses: In some manufacturing contexts, gypsum serves as a filler, filler-coated material, or additive to control setting and thickness in various products. Gypsum also has applications in art and conservation where controlled setting properties are valuable, and in certain medical or dental contexts where casting and mold-making are involved. See Cast (medicine) and Plaster.

Economic significance, markets, and policy context

Gypsum is one of the most economically important industrial minerals because of its ubiquity and the efficiency with which it can be mined and processed. Its availability influences construction costs, housing supply, and infrastructure projects. The global supply chain for gypsum is shaped by mine permitting regimes, environmental standards, transportation costs, and regional demand for drywall and plaster products. Large producers include major manufacturing and mining countries, with regional hubs where building markets are strongest. See Supply chain and Globalization for related market dynamics, and Mining regulation for the policy framework that can influence extraction and processing.

Proponents of a market-friendly approach argue that well-defined property rights, transparent permitting, and predictable regulatory conditions encourage investment in gypsum resources and related infrastructure, reducing costs for builders and homeowners. Critics warn that overbroad or duplicative environmental rules can raise development costs, potentially slowing housing supply and raising construction costs in the short term; in response, many jurisdictions advocate streamlined approvals, targeted environmental protections, and performance-based standards. Advocates for sensible regulation maintain that protecting water quality, air quality, and land integrity ultimately reduces long-run costs by avoiding waste and impairment of productive land. Critics of excessive restrictions sometimes contend that such rules invite delays and escalate project risk, undermining competitiveness; supporters of balanced regulation argue that basic safeguards support long-term prosperity and public welfare. See Environmental regulation and Trade policy for related debates.

A small but growing component of gypsum economics relates to recycling of construction and demolition waste. Recycling gypsum reduces landfill use and can recover material for reuse in new drywall and other products, contributing to resource efficiency and waste reduction. See Recycling and Circular economy for broader discussion of these approaches.