Ammonium minerals

thumb|upright|Salammoniac crystal from Ravat Village, Tajikistan. One of many unusual salammoniac crystal specimens found in the area of Ravat Village, near [[Yaghnob River, where the crystals have grown in a feather-like or three-dimensional arborescent. Size: miniature, 3.3 × 1.4 × 1.4 cm]]

Struvite (magnesium ammonium phosphate) is a phosphate mineral with formula: NH4MgPO4·6H2O. Struvite crystallizes in the orthorhombic system as white to yellowish or brownish-white pyramidal crystals or in platy mica-like forms. It is a soft mineral with Mohs hardness of 1.5 to 2 and has a low specific gravity of 1.7. It is sparingly soluble in neutral and alkaline conditions, but readily soluble in acid.

Buddingtonite is an ammonium feldspar with formula: NH4AlSi3O8 (note: some sources add 0.5H2O to the formula). It forms by hydrothermal alteration of primary feldspar minerals. It is an indicator of possible gold and silver deposits, as they can become concentrated by hydrothermal processes. It crystallizes in the monoclinic crystal system and is colorless to white with a vitreous luster. Its structure is analogous to that of high sanidine (KAlSi3O8). Buddingtonite has a hardness of 5.5 and a specific gravity of 2.32.

Bararite is a natural form of ammonium fluorosilicate (also known as hexafluorosilicate or fluosilicate). It has chemical formula (NH4)2SiF6 and trigonal crystal structure. This mineral was once classified as part of cryptohalite. Bararite is named after the place where it was first described, Barari in Jharia Coal Field, Dhanbad, India. It is found at the fumaroles of volcanoes (Vesuvius, Italy), over burning coal seams (Barari, India), and in burning piles of anthracite (Pennsylvania, U.S.). It is a sublimation product that forms with cryptohalite, sal ammoniac, and native sulfur.

Tschermigite is a mineral form of ammonium alum, formula NH4Al(SO4)2·12(H2O). It is found in burning coal seams, bituminous shale and fumaroles. Because of its extreme water solubility it is unlikely to persist except in the dryest of conditions. Discovered in 1852 at Cermiky, also known as Tschermig in Bohemia. It is colorless and named for where it was discovered.

Mascagnite is a rare ammonium sulfate mineral (NH4)2SO4. It crystallizes in the orthorhombic system typically forming as stalactitic masses exhibiting good cleavage. 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.

Stercorite is the mineral form of microcosmic salt. The name comes from the Latin "stercus", meaning dung, since the mineral was originally discovered among guano.

thumb | right | alt=boussingaultite | boussingaultite Boussingaultite is a rare ammonium magnesium hydrated sulfate mineral of the chemical formula: (NH4)2Mg(SO4)2 · 6 H2O. The formula of boussingaultite is that of Tutton's salts type. It was originally described from geothermal fields in Tuscany, Italy, where it occurs together with its iron analogue mohrite, but is more commonly found on burning coal dumps. The mineral possess monoclinic symmetry and forms clear, often rounded crystals.

Mohrite, (NH4)2Fe(SO4)2·6 H2O, is a rare ammonium iron(II) sulfate mineral originally found in the geothermal fields of Tuscany, Italy. This Fe-dominant analogue of boussingaultite is sometimes reported from burning coal dumps where it is a product of pyrite oxidation.

Letovicite () is an ammonium sulfate mineral with composition (NH4)3H(SO4)2 (IUPAC: triammonium sulfate hydrogensulfate, Nickel–Strunz classification 07.AD.20).

Uramphite is a rarely-found phosphate mineral in the "phosphate, arsenate and vanadate" mineral class with chemical composition (NH4)2[UO2PO4]2·6H2O from which it is seen to be a hydrated ammonium uranyl phosphate.

Ammineite is the first recognized mineral containing ammine groups. Its formula is [CuCl2(NH3)2]. The mineral is chemically pure. It was found in a guano deposit in Chile. At the same site other ammine-containing minerals were later found:

Efremovite is a rare ammonium sulfate mineral with the chemical formula: (NH4)2Mg2(SO4)3. It is a white to gray cubic mineral. This anhydrous sulfate occurs as constituent in sulfate crusts of burning coal dumps. It is hygroscopic and when exposed to humid air it slowly converts to the hydrate form, boussingaultite.

Lecontite (sodium ammonium sulfate dihydrate, with potassium substituting for some ammonium, typically about a fourth) is a sulfate mineral with the formula (NH4,K)NaSO4·2H2O. It was found by John Lawrence LeConte in Las Piedras Cave in Honduras as a breakdown product of bat guano, including crystals up to an inch long and identified as a separate mineral by W.J. Taylor in 1858. As of 1963 most natural specimens came from the same cave.