THE MINERAL SAL AMMONIAC

  • Chemistry: NH4Cl, Ammonium Chloride.
  • Class: Halides
  • Uses: As mineral specimens.
  • Specimens

Sal ammoniac is certainly an oddball mineral. It is composed of ammonium, NH4, and this alone is odd enough. Sal ammoniac is one of the most common and most well known of the ammonium-bearing minerals. These are some other ammonium bearing-minerals:

  • Boussingaultite (Hydrated Ammonium Magnesium Sulfate)
  • Cryptohalite (Ammonium Silicon Fluoride)
  • Guanine (Carbohydrate Ammonium Nitrogen Oxide)
  • Struvite (Hydrated Ammonium Magnesium Phosphate)
  • Tschermigite (Hydrated Ammonium Aluminum Sulfate)

Sal ammoniac forms on volcanic rocks near fume releasing vents. There is no liquid phase as the mineral crystallizes from these fumes in a process called sublimation. The crystallization occurs as the gases are escaping and crystals tend to be short-lived. Sal ammoniac is very soluble in water and crystals will be removed during the first rain of their existence, so to speak, if they are not removed by collectors first.

Other possible natural occurrences exist from underground burning coal seams. Alexander the Great is said to have found sal ammoniac crystals in a cave in a region that is now Tadzhikistan. The region was plagued by underground burning coal seams.

Sal ammoniac can be produced artificially and has its uses. When ammonia fumes are blown across hydrochloric acid; sal ammoniac fumes are produced. The technique is sometimes used to produce sal ammoniac coatings on dark objects that are about to be photographed. This will often enhance a difficult to photograph object by adding detail to the subject.

Natural crystals of sal ammoniac have an unreal or unnatural character to them. They are so small, delicate, intricate and at times quite beautiful that they just do not seem to be like other minerals. But it is sal ammoniac's natural methods of origin that lend themselves to produce these one-of-a-kind specimens.

PHYSICAL CHARACTERISTICS:

  • Color is colorless, white or off-white almost yellow.
  • Luster is vitreous.
  • Transparency: Crystals are transparent to translucent.
  • Crystal System: Isometric; possibly of the gyroidal class 4 3 2.
  • Crystal Habits include cubes, octahedrons and dodecahedrons. Complicated arborescent, snowflake-like and dendritic specimens are available. Crusts and coatings are more common.
  • Cleavage is poor in one direction.
  • Fracture is conchoidal to earthy.
  • Hardness is 1.5 - 2
  • Specific Gravity is 1.5 (very light).
  • Streak is white.
  • Associated Minerals include sodium alum, sulfur and other fumarole minerals.
  • Notable Occurrences include Tadzhikistan; Mt. Vesuvius, Italy and Paricutin Volcano, Michoacan, Mexico.
  • Best Field Indicators are crystal habit, associations, origin of formation, softness and density.
SAL_AMMONIAC specimens:
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SAL_AMMONIAC specimen sal-1
$ 37.00
Dims: 1.1 x 0.8 x 0.7" (2.8 x 2.0 x 1.8 cm)
Wt: 23.2 g w/ specimen box
Scholler Mine, Kladno, Czech Republic
Several very small Sal Ammoniac crystals rest on the rusty, chalky host rock of this specimen. These crystals do not exceed 0.3" (8 mm) along any axis, but appear to be in generally good condition, though a few of the larger ones on the edges of the host rock may be damaged and incomplete. The crystals have excellent and complex cubic-based form, which may be gyroidal. Their edges are relatively well-defined and their faces are clean and possess a luster that ranges widely from waxy to vitreous. All are colorless, transparent, and extremely clear- almost all interference with clarity is caused by surface patinas. The material on which they rest strongly resembles shale, but it is rather rusty. It is also glued to the base of an oblong plastic specimen box with a clear, removable cover.
no photo
sal-1 ($ 37.00)
Scholler Mine, Kladno, Czech Republic
SAL_AMMONIAC specimen sal-2
$ 40.00
Dims: 1.5 x 1.1 x 0.7" (3.8 x 2.8 x 1.8 cm)
Wt: 23.7 g w/ specimen box
Scholler Mine, Kladno, Czech Republic
At least 30 Sal Ammoniac crystals rest on the rusty host rock of this thumbnail specimen. They are generally in excellent condition- almost no damage is visible- and range in diameter from less than 2 mm to nearly 0.3" (8 mm). Though several of them are moderately to severely warped, most have excellent cubic-based crystal form; they commonly take on what appears to be a gyroidal form, though there do appear to be one or two definite trapezohedrons present. All have well-defined edges and clean faces that possess a generally vitreous luster. They are colorless, transparent, and extremely clear, containing almost no visible internal fractures or flaws. The host rock on which they rest has the appearance of a rust-covered shale, and is hot-glued onto the base of an oblong plastic specimen box, whose clear cover is completely removable.
no photo
sal-2 ($ 40.00)
Scholler Mine, Kladno, Czech Republic
SAL_AMMONIAC specimen sal-3
$ 30.00
Dims: 1.2 x 1.0 x 1.0" (3.0 x 2.5 x 2.5 cm)
Wt: 2.5 g
Centralia, Columbia County, Pennsylvania, U.S.A.
This odd little specimen consists of a portion of a "crust" of Sal Ammoniac that was created through fumarolic activity caused by a fire in a coal mine. As the hot exhaust gases escaped, they coated the nearby ground with layers of the ammonium chloride mineral. This particular piece shows absolutely no evidence of crystal form, and has a dull yellow coloration and a matte luster. It is also essentially opaque and has a low mass, due to an almost spongelike internal structure. A few small pieces of what might be a rusty shale base rock are attached.
no photo
sal-3 ($ 30.00)
Centralia, Columbia County, Pennsylvania, U.S.A.
SAL_AMMONIAC specimen sal-4
$ 35.00
Dims: 1.2 x 0.8 x 0.8" (3.0 x 2.0 x 2.0 cm)
Wt: 25.7 g w/ specimen box
Scholler Mine, Kladno, Czech Republic
At least 25 small Sal Ammoniac crystals rest on the iron-bearing host rock of this thumbnail specimen. These crystals range in diameter from 2 mm to 0.2" (6 mm) and are generally in very good condition. Their dodecahedral forms are often very warped due to intergrowth and other growing conditions, but most have excellent form with well-defined edges and clean faces that possess a bright pearly-to-vitreous luster. They are generally colorless, transparent, and very clear, though a few may show interference through rust inclusions from the iron-bearing host rock. The piece is hot-glued into a plastic specimen box.
no photo
sal-4 ($ 35.00)
Scholler Mine, Kladno, Czech Republic
SAL_AMMONIAC specimen sal-5
$ 28.00
Dims: 0.9 x 0.3 x 0.2" (2.3 x 0.8 x 0.5 cm)
Wt: 9.2 g w/ specimen box
Ravat, Tadzikhistan
A few dendritic Sal Ammoniac crystals make up this small specimen. It basically consists of a single dendritic crystal that has sprouted a few noticeable "branches". It is in excellent condition, showing no visible damage, and has exceptional cubic-based form with a high amount of detail. Its milky-white color and dull waxy luster are standard for its species, and it is generally translucent and cloudy. There is no host rock of any sort present, and the piece is affixed to a plastic specimen box with an adhesive putty.
no photo
sal-5 ($ 28.00)
Ravat, Tadzikhistan
SAL_AMMONIAC specimen sal-6
$ 47.00
Dims: 0.9 x 0.2 x 0.2" (2.3x 0.5 x 0.5 cm)
Wt: 15.3 g w/ specimen box
Ravat, Tadzikhistan
A single dendritic formation of Sal Ammoniac makes up this specimen. This formation is made up of several Sal Ammoniac crystals that branch off of a central line of growth. The newer crystals at the top of the formation are smaller than the older ones, giving it a conical, "pine tree" shape. These crystals do not exceed 0.1" (3 mm) in length and are in excellent condition, showing no damage. Their form appears to be quite good, though magnification is needed to properly study it. All have a milky-white color and a dull luster, and are translucent. There is no base or host rock present, and the piece is affixed inside a plastic specimen box with an adhesive putty.
no photo
sal-6 ($ 47.00)
Ravat, Tadzikhistan
SAL_AMMONIAC specimen sal-7
$ 33.00
Dims: 0.6 x 0.5 x 0.2" (1.5 x 1.3 x 0.5 cm)
Wt: 8.5 g
Pamir Mountains, Russia
This small thumbnail specimen consists of a branching, dendritic Sal Ammoniac formation. This formation resembles those that are sometimes formed by such native metals as gold and silver. The Sal Ammoniac shows definite crsytal form, though individual crystals are impossible to discern. The material has a dull white coloration and a pearly luster and is translucent. There is no host rock present, and it is affixed inside a plastic specimen box with a hot glue.
no photo
sal-7 ($ 33.00)
Pamir Mountains, Russia
SAL_AMMONIAC specimen sal-8
$ 25.00
Dims: 1.2 x 0.4 x 0.3" (3.0 x 1.0 x 0.8 cm)
Wt: 1 g
near Ravat Village, Tajikistan
This delicate thumbnail specimen consists of an arborescent formation of Sal Ammoniac Crystals. The formation is in excellent condition, showing almost no damage, and has very good form and symmetry. The Sal Ammoniac itself has a dull white color and a dull matte luster, and is translucent. Several tiny native sulfur crystals have formed along the ridge on the back of the formation- they are well-formed, but magnification is needed to study them. There is no host rock present, however.
no photo
sal-8 ($ 25.00)
near Ravat Village, Tajikistan
 

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