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 |
