Sal ammoniac


Sal ammoniac

Infobox mineral
name = Sal ammoniac
category = Halide Group Mineral
boxwidth =
boxbgcolor =


imagesize =
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formula = NH4Cl
molweight = 53.49 g/mol
color = Colorless, White,
habit = massive, Encrustations
system = Isometric
twinning = on the {111}
cleavage = imperfect on the {111}
fracture = Concoidal
tenacity = Sectile
mohs = 1-2
luster = Vitreous
polish =
refractive =
opticalprop = Isotropic
birefringence = weak after deformation
dispersion =
pleochroism =
fluorescence=
absorption =
streak = White
gravity =
density = 1.535 g/cm3
melt =
fusibility =
diagnostic =
solubility = in water
diaphaneity = Transparent
other =
references = [ [http://www.mindat.org/min-3507.html Salammoniac: Salammoniac mineral information and data ] ] [ [http://webmineral.com/data/Sal-ammoniac.shtml Sal-ammoniac Mineral Data ] ] [http://rruff.geo.arizona.edu/doclib/hom/salammoniac.pdf]

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.

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 Tadzhikistan; Mt. Vesuvius, Italy; and Parícutin, Michoacan, Mexico.

Sal ammoniac is also the archaic name for the chemical compound ammonium chloride; from Greek, ἅλς ἀμμωνιακός "hals ammoniakos", salt of Ammon, because of its early manufacture in Egypt.

It is commonly used as a flux in the soldering of stained-glass windows. In both jewellery-making and the refining of precious metals, potassium carbonate (cream of tartar) is added to gold and silver in a borax-coated crucible to purify iron or steel filings that may have contaminated the scrap. It is then air-cooled and remelted with a one-to-one mixture of powdered charcoal and sal ammoniac to yield a sturdy ingot of the respective metal or alloy in the case of sterling silver (0.75% copper) or karated gold. Anything other than 24-karat gold has silver and copper added. Usually the addition of silica, zinc, and deoxidants in very small amounts relative to the pennyweight (dwt.) of gold are processed into gold from as low as 8-karat to as high as 23.5-karat gold. This is added to prevent porosity or cracking while milling the ingot further into wire, sheet, or tubing. Without those additives an otherwise poor-quality ingot will result in open crucible melting with a hand torch or blowpipe and flame, as was done before electric melting furnaces were invented for use in the precious metals industry. These practices are still used by metalsmiths and jewelers today.

Sal ammoniac has also been used in the past in bakery products to give cookies a very crisp texture, although that application is rapidly dying due to the general disuse of it as an ingredient. However, in some areas of Europe, particularly Scandinavia, it is still widely used in the production of salty licorice candy known as Salmiak. The term sal ammoniac has largely fallen out of general use in the 20th century.

References

* [http://webmineral.com/data/Sal-ammoniac.shtml Webmineral data]
* [http://www.mindat.org/min-3507.html Mindat with location data]
* [http://www.galleries.com/minerals/halides/sal_ammo/sal_ammo.htm Mineral galleries]


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Look at other dictionaries:

  • Sal ammoniac — Sal Sal (s[a^]l), n. [L. See {Salt}.] (Chem. & Pharm.) Salt. [1913 Webster] {Sal absinthii} [NL.] (Old Chem.), an impure potassium carbonate obtained from the ashes of wormwood ({Artemisia Absinthium}). {Sal acetosell[ae]} [NL.] (Old Chem.), salt …   The Collaborative International Dictionary of English

  • Sal ammoniac — Ammoniac Am*mo ni*ac, Ammoniacal Am mo*ni a*cal, a. Of, pertaining, or containing ammonia, or possessing its properties; as, an ammoniac salt; ammoniacal gas. [1913 Webster] {Ammoniacal engine}, an engine in which the vapor of ammonia is used as… …   The Collaborative International Dictionary of English

  • sal ammoniac — n. [ME sal armoniak: see SAL & AMMONIAC] AMMONIUM CHLORIDE …   English World dictionary

  • sal ammoniac — ► NOUN dated ▪ ammonium chloride, a white crystalline salt. ORIGIN Latin sal ammoniacus salt of Ammon , from Greek amm niakos of Ammon , used as a name for the salt and gum obtained near the temple of Jupiter Ammon at Siwa in Egypt …   English terms dictionary

  • sal ammoniac — sal am·mo·ni·ac .sal ə mō nē .ak n AMMONIUM CHLORIDE * * * ammonium chloride …   Medical dictionary

  • sal ammoniac — [ˌsal ə məʊnɪak] noun dated ammonium chloride, a white crystalline salt. Origin ME: from L. sal ammoniacus salt of Ammon ; see word history at ammonia …   English new terms dictionary

  • sal ammoniac — sal′ ammo′niac n. chem. ammonium chloride • Etymology: 1300–50 …   From formal English to slang

  • sal ammoniac — noun Etymology: Middle English sal armoniak, from Latin sal ammoniacus, literally, salt of Ammon Date: 14th century ammonium chloride …   New Collegiate Dictionary

  • sal ammoniac — /sæl əˈmoʊniæk/ (say sal uh mohneeak) noun → ammonium chloride …   Australian English dictionary

  • sal ammoniac — n. ammonium chloride, a white crystalline salt. Etymology: L sal ammoniacus salt of Ammon , associated with the Roman temple of Ammon in N. Africa …   Useful english dictionary


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