Proustite

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title: "Proustite" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["silver-minerals", "arsenic-minerals", "sulfosalt-minerals", "trigonal-minerals", "minerals-in-space-group-167", "blendes"] description: "Sulfosalt mineral" topic_path: "general/silver-minerals" source: "https://en.wikipedia.org/wiki/Proustite" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Sulfosalt mineral ::

::data[format=table title="infobox mineral"]

Field	Value
name	Proustite
category	Sulfosalt minerals
image	Proustite-209739.jpg
imagesize	260px
formula	Ag3AsS3
IMAsymbol	Prs
strunz	2.GA.05
Neso-sulfarsenites
dana	03.04.01.01
Proustite group
system	Trigonal
class	Hexagonal scalenohedral (m)
H-M Symbol: ( 2/m)
symmetry	Rc
unit cell	a = 10.79 Å, c = 8.69 Å; Z = 6
color	Scarlet-vermilion
habit	Crystals prismatic and scalenohedral, massive, compact
twinning	Common
cleavage	Distinct on {101}
fracture	Conchoidal to uneven
tenacity	Brittle
mohs	2 – 2.5
luster	Adamantine
streak	Vermilion
diaphaneity	Translucent, darkens when exposed to light
gravity	5.57 measured, 5.625 calculated
opticalprop	Uniaxial (−)
refractive	nω = 3.087 – 3.088 nε = 2.792
birefringence	δ = 0.295 – 0.296
pleochroism	Moderate; cochineal-red to blood-red
references
::

| name = Proustite | category = Sulfosalt minerals | boxwidth = | boxbgcolor = | image = Proustite-209739.jpg | imagesize = 260px | alt = | caption = | formula = Ag3AsS3 | IMAsymbol = Prs | molweight = | strunz = 2.GA.05 Neso-sulfarsenites | dana = 03.04.01.01 Proustite group | system = Trigonal | class = Hexagonal scalenohedral (m) H-M Symbol: ( 2/m) | symmetry = Rc | unit cell = a = 10.79 Å, c = 8.69 Å; Z = 6 | color = Scarlet-vermilion | colour = | habit = Crystals prismatic and scalenohedral, massive, compact | twinning = Common | cleavage = Distinct on {101} | fracture = Conchoidal to uneven | tenacity = Brittle | mohs = 2 – 2.5 | luster = Adamantine | streak = Vermilion | diaphaneity = Translucent, darkens when exposed to light | gravity = 5.57 measured, 5.625 calculated | density = | polish = | opticalprop = Uniaxial (−) | refractive = nω = 3.087 – 3.088 nε = 2.792 | birefringence = δ = 0.295 – 0.296 | pleochroism = Moderate; cochineal-red to blood-red | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence= | absorption = | melt = | fusibility = | diagnostic = | solubility = | other = | alteration = | references = Proustite is a sulfosalt mineral consisting of silver sulfarsenide, Ag3AsS3, known also as ruby blende, light red silver, arsenic-silver blende or ruby silver ore, and an important source of the metal. It is closely allied to the corresponding sulfantimonide, pyrargyrite, from which it was distinguished by the chemical analyses of Joseph L. Proust (1754–1826) in 1804, after whom the mineral received its name.

The prismatic crystals are often terminated by the scalenohedron and the obtuse rhombohedron, thus resembling calcite (dog-tooth-spar) in habit. The color is scarlet-vermilion and the luster adamantine; crystals are transparent and very brilliant, but on exposure to light they soon become dull black and opaque. The streak is scarlet, the hardness 2 to 2.5, and the specific gravity 5.57. Its transparency differs from specimen to specimen, but most are opaque or translucent.

Proustite occurs in hydrothermal deposits as a phase in the oxidized and supergene zone. It is associated with other silver minerals and sulfides such as native silver, native arsenic, xanthoconite, stephanite, acanthite, tetrahedrite and chlorargyrite.

Magnificent groups of large crystals have been found at Chañarcillo in Chile; other localities which have yielded fine specimens are Freiberg and Marienberg in Saxony, Joachimsthal in Bohemia and Sainte-Marie-aux-Mines in Alsace.

File:Proustite (long prismatic crystal) - Chanarcillo, Copiapo Province, Atacama Region, Chile.jpg|Proustite (long prismatic crystal) – Chañarcillo, Copiapo Province, Chile. Specimen height is 4 cm.

Structure

::figure[src="https://upload.wikimedia.org/wikipedia/commons/f/f0/SubunitProustite.jpg" caption="Subunit of the proustite structure, showing the connectivity of Ag, As (violet), S."] ::

::figure[src="https://upload.wikimedia.org/wikipedia/commons/a/a9/Proustite.jpg" caption="The structure of proustite can be viewed as the Ag⁺ derivative of [AsS₃]³⁻.Engel, P.; Nowacki, W."Die Verfeinerung der Kristallstruktur von Proustit, Ag₃As S₃ und Pyrargyrit, Ag₃SbS₃" Neues Jahrbuch fuer Mineralogie. Monatshefte 1966, p181-p184"] ::

References

References

1. Warr, L.N.. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine.
2. http://rruff.geo.arizona.edu/doclib/hom/proustite.pdf Handbook of Mineralogy
3. http://www.mindat.org/min-3294.html Mindat.org
4. http://www.webmineral.com/data/Proustite.shtml Webmineral
5. "Proustite".
6. "Proustite Value, Price, and Jewelry Information".
7. Engel, P.; Nowacki, W."Die Verfeinerung der Kristallstruktur von Proustit, Ag₃As S₃ und Pyrargyrit, Ag₃SbS₃" Neues Jahrbuch fuer Mineralogie. Monatshefte 1966, p181-p184

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