Mineral phase
IMA name
Pararealgar
Type
Class
non-silicate mineral
Compound type
sulfide
Chemical composition
Formula
$As_4S_4$ or $AsS$
Chemical formula
As4S4
Elemental formula
As4 S4
Isotope mixture type
terrestrial abundance
  Formula Name Family Number min-max Isotope mole fraction State Relevance
$As$ Arsenic element 4 constituent element main
$S$ Sulfur element 4 constituent element main
Chemical bonds
  Bond Number
$As-As$ 2
$As-S$ 8
Oxides comments
As: 70.03%, S: 29.97%

Strunz

Class
sulfides - sufosalts (02)
Division
sulfides of arsenic, alkalies; sulfides with halide, oxide, hydroxide, H2O (02.F)
Family
With As, (Sb), S (02.FA)
Code
02.FA.15b

Dana

Major class
sulfides (II)
Class
sulfides - including selenides and tellurides (02)
Type
where Am Bn Xp, with m:p=1:1 (02.08)
Group
Realgar series (02.08.22)
Code
02.08.22.02
Polymorphs
  • Realgar (molecular isomer of As4S4: three kinds of As centres (and three kinds of S centres))
Phase type
crystalline
Crystal system
monoclinic
Crystal class
prismatic
Crystal class symbol
2/m (C2h)
Crystal spacegroup
P2(1)/c
Molar mass
106.99 $g/mol$
Density
3.52 $g/cm^3$
State NTP
solid
Refringence type
biaxial
Refringence sign
positive
Refraction index $n_{\beta}$
2.02
Pure color
yellow-orange
Color
light yellow, orange brown, orange
Luster
vitreous
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