sedimentary
Wallboard/Drywall (Gypsum-based)
Gypsum (Calcium Sulfate Dihydrate) - CaSO4·2H2O
Hardness: 2 (Mohs scale), Color: White/Light Gray, Luster: Pearly to dull when processed, Crystal Structure: Monoclinic (in mineral form), Cleavage: Perfect in one direction, Specific Gravity: 2.3
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Physical properties
Hardness: 2 (Mohs scale), Color: White/Light Gray, Luster: Pearly to dull when processed, Crystal Structure: Monoclinic (in mineral form), Cleavage: Perfect in one direction, Specific Gravity: 2.3
Formation & geological history
Formed as an evaporite mineral through the evaporation of seawater in marine basins. Modern wallboard is manufactured by dehydrating gypsum into plaster and sandwiching it between paper layers. Geological age varies by source deposit (often Permian or Triassic).
Uses & applications
Primarily used in construction for interior walls and ceilings. It is also used in fertilizer to provide calcium and sulfur to soil.
Geological facts
Gypsum is the most common sulfate mineral. It has a unique property where it can be dehydrated and rehydrated easily, allowing it to be molded into various shapes.
Field identification & locations
In a domestic setting, can be identified by its distinctive layered construction (paper/plaster/paper) and soft, powdery white core. Found ubiquitously in modern residential and commercial structures.
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