Allargentum is a

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. ( ...

from the class of

antimonide Antimonides (sometimes called stibnides) are compounds of antimony with more electropositive elements. The antimonide ion is Sb3−. Reduction of antimony by alkali metals or by other methods leads to alkali metal antimonides of various types. K ...

s, superclass of

sulfide Sulfide (British English also sulphide) is an inorganic anion of sulfur with the chemical formula S2− or a compound containing one or more S2− ions. Solutions of sulfide salts are corrosive. ''Sulfide'' also refers to chemical compounds lar ...

s and

sulfosalt Sulfosalt minerals are sulfide minerals with the general formula , where *A represents a metal such as copper, lead, silver, iron, and rarely mercury, zinc, vanadium *B usually represents semi-metal such as arsenic, antimony, bismuth, and rarely ...

s (sometimes ascribed to the natural elements and

alloy An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductility, ...

s class), with formula written as Ag_1−xSb_x, where x = 0.09–0.16. This moderately rare mineral is found in

silver Silver is a chemical element with the Symbol (chemistry), symbol Ag (from the Latin ', derived from the Proto-Indo-European wikt:Reconstruction:Proto-Indo-European/h₂erǵ-, ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, whi ...

ores and is therefore named from the Greek ἄλλος (''allos'', "another") and the Latin ''argentum'' ("silver"). Its

Vickers hardness The Vickers hardness test was developed in 1921 by Robert L. Smith and George E. Sandland at Vickers Ltd as an alternative to the Brinell method to measure the hardness of materials. The Vickers test is often easier to use than other hardness t ...

is 172–203.

References

Sulfide minerals Sulfosalt minerals Antimonide minerals Silver minerals Alloys Hexagonal minerals Minerals in space group 194 {{mineral-stub