Mascagnite: Properties and Occurrences

Mascagnite is a rare ammonium sulfate mineral (NH4)2SO4. It is a native ammonium sulphate found in volcanic districts. It crystallizes in the orthorhombic system typically forming as stalactitic masses exhibiting good cleavage. It is soluble in water; therefore it is rare. It is soft (not higher than 2.5 on the Mohs Scale) and water-soluble. Optical properties are variable; the purest form is transparent and colorless, but opaque gray or yellow deposits are also known. It occurs in fumaroles, as at Mount Vesuvius. It is a white, crystalline, water-soluble solid, used chiefly as a fertilizer.

General Information

  • Category Sulfate mineral
  • Formula: (repeating unit) (NH4)2SO4
  • Crystal system: Orthorhombic
  • Crystal class: Dipyramidal (mmm)
  • Color: Colorless, grey, yellowish-grey, yellow.

Properties

Mascagnite is an orthorhombic-dipyramidal mineral containing hydrogen, nitrogen, oxygen, and sulfur; a native sulfate of ammonia, found in volcanic districts. It is soft (not higher than 2.5 on the Mohs Scale) and has good cleavage. Optical properties are variable; the purest form is transparent and colorless, but opaque gray or yellow deposits are also known.

  • Cleavage: Distinct/ good On {001}
  • Fracture: Irregular/ uneven
  • Tenacity: Sectile
  • Mohs scale hardness: 2 – ​2 1⁄2
  • Luster: Vitreous, dull
  • Diaphaneity: Transparent, translucent, opaque
  • Density: 1.768 g/cm3

Occurrence: A sublimation product in fumaroles and solfataras; formed by burning coal seams.

It occurs in fumaroles, as at Mount Vesuvius and associated with coal seam fires. It was named for Italian anatomist Paolo Mascagni (1752–1815) who first described the mineral. It is an ammonium sulphate occurring as colorless, grey, or yellowish crystals of the orthorhombic system, usually in translucent crusts formed as sublimation products of volcanoes and burning coal seams, and in Peruvian guano.

Association: Sal ammoniac, tschermigite, sylvite, halite, sassolite, boussingaultite, gypsum, sulfur, cinnabar.

 

Information Source: