U+1F739 ALCHEMICAL SYMBOL FOR SAL-AMMONIAC

U+1F739 was added to Unicode in version 6.0 (2010). It belongs to the block Alchemical Symbols in the Supplementary Multilingual Plane.

This character is a Other Symbol and is commonly used, that is, in no specific script. The character is also known as ammonium chloride.

The glyph is not a composition. It has a Neutral East Asian Width. In bidirectional context it acts as Other Neutral and is not mirrored. In text U+1F739 behaves as Alphabetic regarding line breaks. It has type Other for sentence and Other for word breaks. The Grapheme Cluster Break is Any.

The Wikipedia has the following information about this codepoint:

Sal ammoniac is a rare mineral composed of ammonium chloride, NH₄Cl. It forms colorless to white to yellow-brown crystals in the isometric-hexoctahedral class. It has very poor cleavage and a brittle to conchoidal fracture. It is quite soft, with a Mohs hardness of 1.5 to 2, and has a low specific gravity of 1.5. It is water-soluble. Sal ammoniac is also the archaic name for the chemical compound ammonium chloride. The Romans called the ammonium chloride deposits they collected from near the Temple of Jupiter Amun (Greek Ἄμμων Ammon) in ancient Libya 'sal ammoniacus' (salt of Amun) because of proximity to the nearby temple. Salts of ammonia have been known from very early times; thus the term Hammoniacus sal appears in the writings of Pliny, although it is not known whether the term is identical with the more modern sal-ammoniac. In any case, this salt ultimately gave ammonia and ammonium compounds their name.

It typically forms as encrustations formed by sublimation around volcanic vents. It is found around volcanic fumaroles, guano deposits and burning coal seams. Associated minerals include sodium alum, native sulfur and other fumarole minerals. Notable occurrences include Tajikistan; Mt. Vesuvius, Italy; and Parícutin, Michoacan, Mexico.