Gypsum

**Historical and Cultural Aspects**:
– The word ‘gypsum’ is derived from the Greek word ‘gypsos,’ meaning plaster.
– Quarries in the Montmartre district of Paris provided burnt gypsum known as plaster of Paris.
– Johann Friderich Mayer promoted gypsum’s use as a fertilizer in the 18th century.
– The Plaster War of 1820 was fueled by American farmers’ demand for gypsum.
– Gypsum has historical significance as a construction material and in agriculture.
– Gypsum has been utilized in German agriculture since ancient times.

**Physical Properties and Crystal Varieties**:
– Gypsum crystals are soft and can bend under hand pressure.
– Gypsum is moderately water-soluble and exhibits retrograde solubility.
– Gypsum’s structure consists of layers of calcium and sulfate ions bonded by water molecules.
– Gypsum occurs as flattened crystals, selenite, and granular forms like alabaster.
– Alabaster, a fine-grained variety of gypsum, is used for ornamental work.
– Gypsum can be transparent, opaque, or fibrous in different forms.

**Occurrence and Synthesis**:
– Gypsum is commonly found in thick evaporite beds with sedimentary rocks.
– Gypsum can form in caves, such as the Naica Mine in Mexico, with large crystals.
– Synthetic gypsum is a by-product of industrial processes like flue gas desulfurization.
– Gypsum scaling in brackish water desalination affects membrane life.
– White Sands National Park in New Mexico has extensive gypsum sand deposits.
– Gypsum by-product from desulfurization is used in water treatment and construction.

**Industrial Applications and Occupational Safety**:
– Gypsum is widely used in construction, Portland cement, and agriculture.
– OSHA sets legal exposure limits for gypsum in the workplace.
– NIOSH provides recommended exposure limits for gypsum.
– Compliance with exposure limits is crucial in U.S. workplaces.
– Gypsum is approved as a food additive.
– Proper handling and disposal of gypsum are essential for safety.

**Scientific Studies and Agricultural Benefits**:
– Studies on gypsum include solubility, crystal growth kinetics, and environmental impacts.
– Gypsum plays a role in managing sodic soils and improving soil water potential.
– The chemistry of sodic soil reclamation with gypsum and lime has been studied.
– The Soil Science Society of America recognizes gypsum as an agricultural product.
– Gypsum application in agriculture aids in improving soil structure and crop yield.https://en.wikipedia.org/wiki/Gypsum