Natron

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Natron is a naturally occurring mixture of hydrated sodium carbonate (soda ash, Na2CO3·10 H2O) and about 17% sodium bicarbonate (baking soda, NaHCO3) along with small quantities of household salt (sodium chloride) and sodium sulfate. Natron is white to colorless when pure, varying to gray or yellow with impurities. Natron deposits occur naturally as a part of saline lake beds in arid environments. Historically natron had many practical applications which still resonate in the wide modern use of its constituent mineral components.

Etymology

The English word natron is a French cognate derived from the Spanish natrón through the Arabic natrun from Greek nitron. The modern chemical symbol for sodium, Na, is an abbreviation of that element's new Latin name natrium, which was derived from natron.

Chemical properties

Natron has a specific gravity of 1.42 to 1.47 and a Mohs hardness of 1. It crystallizes in the monoclinic crystal system, typically forming efflorescences and encrustations. Natron effloresces (loses water) in dry air and is partially transformed into the monohydrate thermonatrite, Na2(CO3)·(H2O). The mineral is often found in association with thermonatrite, trona, mirabilite, gaylussite, gypsum and calcite.

Importance in antiquity

Natron was harvested directly from dry lake beds in ancient Egypt and has been used for thousands of years as a cleaning product for both the home and body. Blended with oil, it was an early form of soap. It softens water whilst removing oil, grease and alcohol stains. Undiluted, natron was a cleanser for the teeth and an early mouthwash. The mineral was mixed into early antiseptics for wounds and minor cuts. Natron can be used to dry and preserve fish and meat. It was also an ancient household insecticide.

The mineral was used in Egyptian mummification because it absorbs water and behaves as a drying agent. Moreover, when exposed to moisture the bicarbonate in natron increases pH, which creates a hostile environment for bacteria. Culturally, natron was generally thought to enhance spiritual safety for both the living and the dead. Natron was added to castor oil to make a smokeless fuel which allowed Egyptian artisans to paint elaborate artworks inside ancient tombs without staining them with soot.

Natron is an ingredient for the making of a distinct color called Egyptian blue. It was used along with sand in ceramic and glass making by the Romans and others at least until 640 CE. The mineral was also employed as a flux to solder precious metals together.

Declining use

Most of natron's uses both in the home and by industry were gradually replaced with often closely related sodium compounds and minerals. Natron's detergent properties are now commercially supplied by soda ash (the compound's chief ingredient) and other chemicals. Soda ash also replaced natron in glassmaking. Many of its ancient household roles are now filled by ordinary baking soda, natron's secondary ingredient.

Geological occurrence

See also

Saltpeter

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