Natron is a naturally occurring mixture of

sodium carbonate Sodium carbonate (also known as washing soda, soda ash, sal soda, and soda crystals) is the inorganic compound with the formula and its various hydrates. All forms are white, odourless, water-soluble salts that yield alkaline solutions in water ...

decahydrate ( Na₂CO₃·10H₂O, a kind of

soda ash Sodium carbonate (also known as washing soda, soda ash, sal soda, and soda crystals) is the inorganic compound with the formula and its various hydrates. All forms are white, odourless, water-soluble salts that yield alkaline solutions in water ...

) and around 17%

sodium bicarbonate Sodium bicarbonate ( IUPAC name: sodium hydrogencarbonate), commonly known as baking soda or bicarbonate of soda (or simply “bicarb” especially in the UK) is a chemical compound with the formula NaHCO3. It is a salt composed of a sodium cat ...

(also called baking soda, NaHCO₃) along with small quantities of

sodium chloride Sodium chloride , commonly known as Salt#Edible salt, edible salt, is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. It is transparent or translucent, brittle, hygroscopic, and occurs a ...

and

sodium sulfate Sodium sulfate (also known as sodium sulphate or sulfate of soda) is the inorganic compound with formula Na2SO4 as well as several related hydrates. All forms are white solids that are highly soluble in water. With an annual production of 6 mill ...

. Natron is white to colourless when pure, varying to gray or yellow with impurities. Natron deposits are sometimes found in saline lake beds which arose in arid environments. Throughout history natron has had many practical applications that continue today in the wide range of modern uses of its constituent mineral components. In modern

mineralogy Mineralogy is a subject of geology specializing in the scientific study of the chemistry, crystal structure, and physical (including optical mineralogy, optical) properties of minerals and mineralized artifact (archaeology), artifacts. Specific s ...

the term ''natron'' has come to mean only the sodium carbonate decahydrate (hydrated soda ash) that makes up most of the historical salt.

Etymology

The English and German word ''natron'' is a French

cognate In historical linguistics, cognates or lexical cognates are sets of words that have been inherited in direct descent from an etymological ancestor in a common parent language. Because language change can have radical effects on both the s ...

derived through the Spanish ''natrón'' from

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

''natrium'' and

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

''nitron'' (). This derives from the

Ancient Egyptian Ancient Egypt () was a cradle of civilization concentrated along the lower reaches of the Nile River in Northeast Africa. It emerged from prehistoric Egypt around 3150BC (according to conventional Egyptian chronology), when Upper and Lower E ...

word ''nṯrj''. ''Natron'' refers to

Wadi El Natrun Wadi El Natrun (Arabic: "Valley of Natron"; , "measure of the hearts") is a Depression (geology), depression in northern Egypt that is located below sea level and below the Nile River level. The valley contains several alkaline lakes, natron- ...

or Natron Valley in Egypt, from which natron was mined by the ancient Egyptians for use in burial rites. The modern chemical symbol for

sodium Sodium is a chemical element; it has Symbol (chemistry), symbol Na (from Neo-Latin ) and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 element, group 1 of the peri ...

, ''Na'', is an abbreviation of that element's

Neo-Latin Neo-LatinSidwell, Keith ''Classical Latin-Medieval Latin-Neo Latin'' in ; others, throughout. (also known as New Latin and Modern Latin) is the style of written Latin used in original literary, scholarly, and scientific works, first in Italy d ...

name ''natrium'', which was derived from ''natron''. The name of the chemical element

Nitrogen Nitrogen is a chemical element; it has Symbol (chemistry), symbol N and atomic number 7. Nitrogen is a Nonmetal (chemistry), nonmetal and the lightest member of pnictogen, group 15 of the periodic table, often called the Pnictogen, pnictogens. ...

is also a cognate to natron, it derives from Greek ''nitron'' and ''-gen (''a producer of something, in this case

Nitric acid Nitric acid is an inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but samples tend to acquire a yellow cast over time due to decomposition into nitrogen oxide, oxides of nitrogen. Most com ...

, which was produced from

niter Niter or nitre is the mineral form of potassium nitrate, KNO3. It is a soft, white, highly soluble mineral found primarily in arid climates or cave deposits. Potassium and other nitrates are of great importance for use in fertilizers and, hi ...

(nitre) (potassium nitrate)). Niter was also an obsolete name for natron because in earlier times, both minerals used to be confused with each other.

Importance in antiquity

Historical natron was harvested directly as a salt mixture from dry lake beds in

ancient Egypt Ancient Egypt () was a cradle of civilization concentrated along the lower reaches of the Nile River in Northeast Africa. It emerged from prehistoric Egypt around 3150BC (according to conventional Egyptian chronology), when Upper and Lower E ...

, 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 Soap is a salt (chemistry), salt of a fatty acid (sometimes other carboxylic acids) used for cleaning and lubricating products as well as other applications. In a domestic setting, soaps, specifically "toilet soaps", are surfactants usually u ...

. It softens water while removing oil and grease. Undiluted, natron was a cleanser for the teeth and an early

mouthwash Mouthwash, mouth rinse, oral rinse, or mouth bath is a liquid which is held in the mouth passively or swirled around the mouth by contraction of the perioral muscles and/or movement of the head, and may be gargled, where the head is tilted back ...

. The mineral was mixed into early

antiseptics An antiseptic ( and ) is an antimicrobial substance or compound that is applied to living tissue to reduce the possibility of sepsis, infection, or putrefaction. Antiseptics are generally distinguished from ''antibiotics'' by the latter's abili ...

for wounds and minor cuts. Natron can be used to dry and preserve fish and meat. It was also an ancient household insecticide, and was used for making leather as well as a bleach for clothing. The mineral was used during

mummification A mummy is a dead human or an animal whose soft tissues and organs have been preserved by either intentional or accidental exposure to chemicals, extreme cold, very low humidity, or lack of air, so that the recovered body does not decay furt ...

ceremonies in ancient Egypt because it absorbs water and behaves as a drying agent. Moreover, when exposed to moisture, the

carbonate A carbonate is a salt of carbonic acid, (), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word "carbonate" may also refer to a carbonate ester, an organic compound containing the carbonate group ...

in natron increases pH (raises

alkalinity Alkalinity (from ) is the capacity of water to resist Freshwater acidification, acidification. It should not be confused with base (chemistry), basicity, which is an absolute measurement on the pH scale. Alkalinity is the strength of a buffer s ...

), which creates a hostile environment for bacteria. In some cultures, natron was thought to enhance spiritual safety for both the living and the dead. Natron was added to

castor oil Castor oil is a vegetable oil pressed from castor beans, the seeds of the plant ''Ricinus communis''. The seeds are 40 to 60 percent oil. It is a colourless or pale yellow liquid with a distinct taste and odor. Its boiling point is and its den ...

to make a

smokeless fuel Smokeless fuel is a type of solid fuel which either does not emit visible smoke or emits minimal amounts during combustion. These types of fuel find use where the use of fuels which produce smoke, such as coal and unseasoned or wet wood, is prohi ...

, which allowed Egyptian artisans to paint elaborate artworks inside ancient tombs without staining them with soot. The Pyramid Texts describe how natron pellets were used as funerary offerings in the rites for the deceased pharaoh, "N". The ceremony required two kinds of natron, one sourced from northern (Lower) and one from southern (Upper) Egypt. Natron is an ingredient for making a distinct color called '' Egyptian blue'', and also as the

flux Flux describes any effect that appears to pass or travel (whether it actually moves or not) through a surface or substance. Flux is a concept in applied mathematics and vector calculus which has many applications in physics. For transport phe ...

Egyptian faience Egyptian faience is a sintered-quartz ceramic material from Ancient Egypt. The sintering process "covered he materialwith a true vitreous coating" as the quartz underwent vitrification, creating a bright lustre of various colours "usually in ...

. It was used along with

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is usually defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural ...

and lime in ceramic and glass-making by the Romans and others at least until AD 640. The mineral was also employed as a flux to solder precious metals together.

Decline in use

Most of natron's uses both in the home and by industry were gradually replaced with closely related sodium compounds and minerals. Natron's

detergent A detergent is a surfactant or a mixture of surfactants with Cleanliness, cleansing properties when in Concentration, dilute Solution (chemistry), solutions. There are a large variety of detergents. A common family is the alkylbenzene sulfonate ...

properties are now commercially supplied by

(pure sodium carbonate), the mixture's chief compound ingredient, along with other chemicals. Soda ash also replaced natron in glass-making. Some of its ancient household roles are also now filled by ordinary

baking soda Sodium bicarbonate (IUPAC name: sodium hydrogencarbonate), commonly known as baking soda or bicarbonate of soda (or simply “bicarb” especially in the UK) is a chemical compound with the formula NaHCO3. It is a salt (chemistry), salt compose ...

, which is

, natron's other key ingredient.

Chemistry of hydrated sodium carbonate

Natron is also the mineralogical name for the compound sodium carbonate decahydrate (Na₂CO₃·10H₂O), which is the main component in historical natron.Sodium carbonate decahydrate has a

specific gravity Relative density, also called specific gravity, is a dimensionless quantity defined as the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for solids and liquids is nea ...

of 1.42 to 1.47 and a

Mohs hardness The Mohs scale ( ) of mineral hardness is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fair ...

of 1. It crystallizes in the

monoclinic In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three Vector (geometric), vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in t ...

-domatic

crystal system In crystallography, a crystal system is a set of point groups (a group of geometric symmetries with at least one fixed point). A lattice system is a set of Bravais lattices (an infinite array of discrete points). Space groups (symmetry groups ...

, typically forming efflorescences and encrustations. The term ''hydrated sodium carbonate'' is commonly used to encompass the monohydrate (Na₂CO₃·H₂O), the decahydrate and the heptahydrate (Na₂CO₃·7H₂O), but is often used in industry to refer to the decahydrate only. Both the hepta- and the decahydrate effloresce (lose water) in dry air and are partially transformed into the monohydrate

thermonatrite Thermonatrite is a naturally occurring evaporite mineral form of sodium carbonate, Na2CO3·H2O. It was first described in 1845. Its name is from the Greek θερμός ''thermos'', "heat", plus ''natron'', because it may be a dehydration product ...

Na₂CO₃·H₂O.

As a source of soda ash

Sodium carbonate decahydrate is stable at room temperature but recrystallizes at only to sodium carbonate heptahydrate, Na₂CO₃·7H₂O, then above to sodium carbonate monohydrate, Na₂CO₃·H₂O. This recrystallization from decahydrate to monohydrate releases much crystal water in a mostly clear, colorless salt solution with little solid

. The mineral natron is often found in association with

, nahcolite,

trona Trona (trisodium hydrogendicarbonate dihydrate, also sodium sesquicarbonate dihydrate, Na2CO3·NaHCO3·2H2O) is a non- marine evaporite mineral. It is mined as the primary source of sodium carbonate in the United States, where it has replaced ...

halite Halite ( ), commonly known as rock salt, is a type of salt, the mineral (natural) form of sodium chloride ( Na Cl). Halite forms isometric crystals. The mineral is typically colorless or white, but may also be light blue, dark blue, purple, pi ...

mirabilite Mirabilite, also known as Glauber's salt, is a hydrous sodium sulfate mineral with the chemical formula Na2SO4·10H2O. It is a vitreous, colorless to white monoclinic mineral that forms as an evaporite from sodium sulfate-bearing brines. It is ...

, gaylussite,

gypsum Gypsum is a soft sulfate mineral composed of calcium sulfate Hydrate, dihydrate, with the chemical formula . It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, drywall and blackboard or sidewalk ...

, and

calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

. Most industrially produced sodium carbonate is soda ash (sodium carbonate anhydrate Na₂CO₃) which is obtained by calcination (dry heating at temperatures of 150 to 200 °C) of sodium bicarbonate, sodium carbonate monohydrate, or

Geological occurrence

Geologically, the mineral natron as well as the historical natron are formed as transpiro-

evaporite An evaporite () is a water- soluble sedimentary mineral deposit that results from concentration and crystallization by evaporation from an aqueous solution. There are two types of evaporite deposits: marine, which can also be described as oce ...

minerals, i.e. crystallizing during the drying up of salt lakes rich in sodium carbonate. The sodium carbonate is usually formed by absorption of

carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...

from the atmosphere by a highly alkaline, sodium-rich lake

brine Brine (or briny water) is a high-concentration solution of salt (typically sodium chloride or calcium chloride) in water. In diverse contexts, ''brine'' may refer to the salt solutions ranging from about 3.5% (a typical concentration of seawat ...

, according to the following reaction scheme: Pure deposits of sodium carbonate decahydrate are rare, due to the limited temperature stability of this compound and due to the fact that the absorption of

usually produces mixtures of

bicarbonate In inorganic chemistry, bicarbonate (IUPAC-recommended nomenclature: hydrogencarbonate) is an intermediate form in the deprotonation of carbonic acid. It is a polyatomic anion with the chemical formula . Bicarbonate serves a crucial bioche ...

and

in solution. From such mixtures, the mineral natron (and also the historical one) will be formed only if the

temperature during evaporation is maximally about – or the

of the lake is so high, that little

is present in solution (see reaction scheme above) – in which case the maximum temperature is increased to about . In most cases the mineral natron will form together with some amount of nahcolite (

), resulting in salt mixtures like the historical natron. Otherwise, the minerals

and nahcolite are commonly formed. As the evaporation of a salt lake will occur over geological time spans, during which also part or all of the salt beds might redissolve and recrystallize, deposits of sodium carbonate can be composed of layers of all these minerals. The following list may include geographical sources of either natron or other hydrated sodium carbonate minerals: * Africa **

Chad Chad, officially the Republic of Chad, is a landlocked country at the crossroads of North Africa, North and Central Africa. It is bordered by Libya to Chad–Libya border, the north, Sudan to Chad–Sudan border, the east, the Central Afric ...

*** shores of

Lake Chad Lake Chad (, Kanuri language, Kanuri: ''Sádǝ'', ) is an endorheic freshwater lake located at the junction of four countries: Nigeria, Niger, Chad, and Cameroon, in western and central Africa respectively, with a catchment area in excess of . ...

*** Trou au Natron ***Era Kohor crater on Emi Koussi **

Egypt Egypt ( , ), officially the Arab Republic of Egypt, is a country spanning the Northeast Africa, northeast corner of Africa and Western Asia, southwest corner of Asia via the Sinai Peninsula. It is bordered by the Mediterranean Sea to northe ...

***

(Natron Valley) **

Ethiopia Ethiopia, officially the Federal Democratic Republic of Ethiopia, is a landlocked country located in the Horn of Africa region of East Africa. It shares borders with Eritrea to the north, Djibouti to the northeast, Somalia to the east, Ken ...

*** Showa Province **

Niger Niger, officially the Republic of the Niger, is a landlocked country in West Africa. It is a unitary state Geography of Niger#Political geography, bordered by Libya to the Libya–Niger border, north-east, Chad to the Chad–Niger border, east ...

*** Bilma **

Tanzania Tanzania, officially the United Republic of Tanzania, is a country in East Africa within the African Great Lakes region. It is bordered by Uganda to the northwest; Kenya to the northeast; the Indian Ocean to the east; Mozambique and Malawi to t ...

Kenya Kenya, officially the Republic of Kenya, is a country located in East Africa. With an estimated population of more than 52.4 million as of mid-2024, Kenya is the 27th-most-populous country in the world and the 7th most populous in Africa. ...

***

Lake Natron Lake Natron is a salt lake, salt or soda lake, alkaline lake located in north Ngorongoro District of Arusha Region in Tanzania with its far northern end crossing into Kenya. It is in the Gregory Rift, which is the eastern branch of the East A ...

* Europe **

Hungary Hungary is a landlocked country in Central Europe. Spanning much of the Pannonian Basin, Carpathian Basin, it is bordered by Slovakia to the north, Ukraine to the northeast, Romania to the east and southeast, Serbia to the south, Croatia and ...

***

Bács-Kiskun County Bács-Kiskun (, ) is a county (''vármegye'' in Hungarian) located in southern Hungary. It was created by the merger of the pre-World War II Bács-Bodrog and the southern parts of Pest-Pilis-Solt-Kiskun counties. With an area of 8,445 km2, ...

, (Great Hungarian Plain) *** Szabolcs-Szatmár-Bereg County (Great Hungarian Plain) **

Italy Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...

***

Campania Campania is an administrative Regions of Italy, region of Italy located in Southern Italy; most of it is in the south-western portion of the Italian Peninsula (with the Tyrrhenian Sea to its west), but it also includes the small Phlegraean Islan ...

***

Province of Naples The province of Naples (; ) was a province in the Campania region of Italy. In 2014/2015, the reform of local authorities (Law 142/1990 and Law 56/2014), replaced the province of Naples with the Metropolitan City of Naples. Demographics The p ...

*** Somma-Vesuvius Complex **

Kola Peninsula The Kola Peninsula (; ) is a peninsula in the extreme northwest of Russia, and one of the largest peninsulas of Europe. Constituting the bulk of the territory of Murmansk Oblast, it lies almost completely inside the Arctic Circle and is border ...

, northern

Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...

*** Khibiny Massif ***

Lovozero Massif The Lovozero Massif (, ''Lovozyorskiye Tundry'', named after the lake in that area – Lake Lovozero; the region is also known as , ''Lovozyorye'') is a mountain range located in the center of the Kola Peninsula in Russia, between Lovozero and ...

**** Alluaiv Mountain **** Kedykverpakhk Mountain *** Umbozero Mine **

England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...

, UK *** St Just District *** Botallack – Pendeen Area * North America **

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

***

Quebec Quebec is Canada's List of Canadian provinces and territories by area, largest province by area. Located in Central Canada, the province shares borders with the provinces of Ontario to the west, Newfoundland and Labrador to the northeast, ...

**** Rouville County **** Mont-Saint-Hilaire *** Interior

British Columbia British Columbia is the westernmost Provinces and territories of Canada, province of Canada. Situated in the Pacific Northwest between the Pacific Ocean and the Rocky Mountains, the province has a diverse geography, with rugged landscapes that ...

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

***

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

**** Inyo County ***

Nevada Nevada ( ; ) is a landlocked state in the Western United States. It borders Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the seventh-most extensive, th ...

**** Churchill County ( Soda Lake District) **** Humboldt County **** Mineral County ***

Oregon Oregon ( , ) is a U.S. state, state in the Pacific Northwest region of the United States. It is a part of the Western U.S., with the Columbia River delineating much of Oregon's northern boundary with Washington (state), Washington, while t ...

**** Lake County ***

Pennsylvania Pennsylvania, officially the Commonwealth of Pennsylvania, is a U.S. state, state spanning the Mid-Atlantic (United States), Mid-Atlantic, Northeastern United States, Northeastern, Appalachian, and Great Lakes region, Great Lakes regions o ...

**** Karns **** Natrona *** Washington **** Okanogan County ***

Wyoming Wyoming ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States, Western United States. It borders Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho t ...

**** Natrona County

References

External links

{{Commons category
Etymology of "natron"
Carbonate minerals Sodium minerals Desiccants Antiseptics Alchemical substances Monoclinic minerals Industrial minerals