Editing Natron (section)

== Chemistry of hydrated sodium carbonate ==
Natron is also the mineralogical name for the compound sodium carbonate decahydrate (Na<sub>2</sub>CO<sub>3</sub>'''·'''10H<sub>2</sub>O), which is the main component in historical natron.<ref name="Webmin"/>Sodium carbonate decahydrate has a [[specific gravity]] of 1.42 to 1.47 and a [[Mohs hardness]] of 1. It crystallizes in the [[monoclinic]]-domatic [[crystal system]], typically forming efflorescences and encrustations.

The term ''hydrated sodium carbonate'' is commonly used to encompass the monohydrate (Na<sub>2</sub>CO<sub>3</sub>'''·'''H<sub>2</sub>O), the decahydrate and the heptahydrate (Na<sub>2</sub>CO<sub>3</sub>'''·'''7H<sub>2</sub>O), 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]] Na<sub>2</sub>CO<sub>3</sub>'''·'''H<sub>2</sub>O.

=== As a source of soda ash ===
Sodium carbonate decahydrate is stable at room temperature but recrystallizes at only {{convert|32|°C|°F|abbr=on}} to sodium carbonate heptahydrate, Na<sub>2</sub>CO<sub>3</sub>'''·'''7H<sub>2</sub>O, then above {{convert|37|-|38|C|F}} to sodium carbonate monohydrate, Na<sub>2</sub>CO<sub>3</sub>'''·'''H<sub>2</sub>O. 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 Na<sub>2</sub>CO<sub>3</sub>) which is obtained by calcination (dry heating at temperatures of 150 to 200&nbsp;°C) of sodium bicarbonate, sodium carbonate monohydrate, or [[trona]].