Allargentum

Allargentum is a mineral from the class of antimonides, superclass of sulfides and sulfosalts (sometimes ascribed to the natural elements and alloys class), with formula written as Ag_1−xSb_x, where x = 0.09–0.16. This moderately rare mineral is found in silver ores and is therefore named from the Greek ἄλλος (allos, "another") and the Latin argentum ("silver"). Its Vickers hardness is 172–203.^[2]

Allargentum
Allargentum on carbonate; size 3.2×2.7×1.4 cm
General
Category	Sulfide mineral
Formula	Ag1−xSbx
IMA symbol	All[1]
Strunz classification	2.AA.30
Dana classification	02.02.01.02
Crystal system	Hexagonal
Crystal class	Dihexagonal dipyramidal (6/mmm) H-M symbol: (6/m 2/m 2/m)
Space group	P63/mmc
Unit cell	a = 2.945, c = 4.77 [Å], Z = 2
Identification
Color	Silver gray
Mohs scale hardness	4
Luster	Metallic
Diaphaneity	Opaque
Specific gravity	10.0 (meas.), 10.12 (calc.)
References	[2][3]