Natron
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Natron | ||
---|---|---|
2V angle Measured: 71° , Calculated: 80° | | |
Solubility | Soluble in water | |
References | [2][3][4] |
Natron is a naturally occurring mixture of
In modern mineralogy 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
Importance in antiquity
Historical natron was harvested directly as a salt mixture from dry lake beds in
The mineral was used during mummification ceremonies in ancient Egypt because it absorbs water and behaves as a drying agent. Moreover, when exposed to moisture, the carbonate in natron increases pH (raises alkalinity), 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 to make a smokeless fuel, 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.
Smin, smin opens thy mouth. One pellet of natron.
O N., thou shalt taste its taste in front of the sḥ-ntr-chapels. One pellet of natron.
That which Horus spits out is smin. One pellet of natron.
That which Set spits out is smin. One pellet of natron.
That which the two harmonious gods (spit out) is smin. One pellet of natron.
To say four times: Thou hast purified thyself with natron, together with Horus (and) the Followers of Horus. Five pellets of natron from Nekheb, Upper Egypt.
Thou purifiest (thyself); Horus purifies (himself). One pellet of natron. Thou purifiest (thyself); Set purifies (himself). One pellet of natron.
Thou purifiest (thyself); Thot purifies (himself). One pellet of natron. Thou purifiest (thyself); the god purifies (himself). One pellet of natron.
Thou also purifiest (thyself)—thou who art among them. One pellet of natron.
Thy mouth is the mouth of a sucking calf on the day of his birth.
Five pellets of natron of the North, Wadi Natrûn (št-p.t)[5]
Natron is an ingredient for making a distinct color called
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
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.
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 Na2CO3·H2O.
As a source of soda ash
Sodium carbonate decahydrate is stable at room temperature but recrystallizes at only 32 °C (90 °F) to sodium carbonate heptahydrate, Na2CO3·7H2O, then above 37–38 °C (99–100 °F) 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 thermonatrite. The mineral natron is often found in association with thermonatrite, nahcolite, trona, halite, mirabilite, gaylussite, gypsum, and calcite. 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 trona.
Geological occurrence
Geologically, the mineral natron as well as the historical natron are formed as transpiro-evaporite 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 from the atmosphere by a highly alkaline, sodium-rich lake brine, 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 carbon dioxide usually produces mixtures of bicarbonate and carbonate in solution. From such mixtures, the mineral natron (and also the historical one) will be formed only if the brine temperature during evaporation is maximally about 20 °C (68 °F) – or the alkalinity of the lake is so high, that little bicarbonate is present in solution (see reaction scheme above) – in which case the maximum temperature is increased to about 30 °C (86 °F). In most cases the mineral natron will form together with some amount of nahcolite (sodium bicarbonate), resulting in salt mixtures like the historical natron. Otherwise, the minerals trona[6] or thermonatrite 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
- shores of Lake Chad
- Trou au Natron
- Era Kohor crater on Emi Koussi
- Egypt
- Wadi El Natrun (Natron Valley)
- Ethiopia
- Niger
- Tanzania
- Chad
- Europe
- Hungary
- Bács-Kiskun County, (Great Hungarian Plain)
- Szabolcs-Szatmár-Bereg County(Great Hungarian Plain)
- Italy
- Campania
- Province of Naples
- Somma-VesuviusComplex
- Kola Peninsula, northern Russia
- Khibiny Massif
- Lovozero Massif
- Alluaiv Mountain
- Kedykverpakhk Mountain
- UmbozeroMine
- England, UK
- St Just District
- Botallack – Pendeen Area
- Hungary
- North America
See also
- Nahcolite
- Niter
- Potassium nitrate
- Shortite
- Soda (disambiguation)
- Sodium sesquicarbonate
- Thermonatrite
- Trona
References
- S2CID 235729616.
- ^ "Natron Mindat". mindat.org. Retrieved 2022-11-28.
- ^ "Natron Handbook" (PDF). Retrieved 2022-11-28.
- ^ a b "Natron Mineral Data". webmineral.com. Retrieved 2022-11-26.
- ^ www.sacred-texts.com/egy/pyt/pyt05.htm The Pyramid Texts, Utterance 35. Translated by Samuel A. B. Mercer, 1952. Accessed 9 April 2020.
- ^ "Trona Mineral Data".