Salammoniac

Salammoniac is a rare Halide mineral composed of ammonium chloride (NH4Cl). Salammoniac is very difficult to facet because it is water soluble, very soft (Mohs hardness of 1.5 -2.0) and has a very low specific gravity of 1.5. It forms as some of the most interesting and collectable crystal shapes in the mineral world. These complex, intricate crystals are white to colorless and often shaped like twisted spines with four sets of crystals radiating out from and twisting around the center spine at 90 degrees from each other.

Salammoniac is a sublimation product that forms around volcanic fume release vents or fumaroles. The crystallization occurs as volcanic gases escape. Another natural occurrence is from underground burning coal seams. The ammonia usually is derived from organic matter. Notable occurrences include Tajikistan; Mt. Vesuvius, Italy; and Parícutin, Michoacan, Mexico. The localtion most known for the unique “spine-like” crystals is the former Ravat Village, Yagnob River, Viloyati Sogd, Tajikistan.

Chemical Formula: NH4Cl
  Ammonium Chloride
Molecular Weight: 53.49 gm
Composition: Hydrogen 7.54 % H —  % Calc as (NH4)2O
  Nitrogen 26.19 % N 48.68 % (NH4)2O
  Chlorine 66.28 % Cl 66.28 % Cl
    —  % Cl -14.96 % —O=Cl2
    100.00 %   100.00 % = TOTAL OXIDE

 

Crystallography: Isometric – Hexoctahedral
Crystal Habit: Crystals usually trapezohedral {112} modified by {113} at times; less commonly with gyroidal forms alone, or in combination. Dodecahedral; cubic (rare). Crystals often exhibit curved or stepped faces and may present a tetragnal or rhombohedral appearance due to suppression of faces and distortion. Skeletal or dendritic aggregates. Crusts or stalactitic masses; fibrous, earthy or mealy.
Twinning: On {111}, may be cyclic
Parting: Translation gliding with T{011}, t[001]

 

Cleavage: Imperfect on {111}
Fracture: Conchoidal
Tenacity: Between brittle and sectile; very plastic
Moh’s Hardness: 1.5 – 2.0
Density: 1.532 (g/cm3)
Luminescence: None
Radioactivity: Not Radioactive
Other: Water Soluble

 

Color: White, pale Gray, may be pale Yellow to Brown if impure; Colorless in transmitted light.
Transparency: Transparent
Luster: Vitreous
Refractive Index: 1.693  Isotropic; may be weakly anisotropic
Birefringence: 0.00 (Isotropic) Weakly birefringent at times, especially after mechanical deformation.
Dispersion: n/a
Pleochroism: None