Pyrite

  • pyrite
    2780m-pyrite1.jpg
    pyrite cubic crystals on marl from navajún, la rioja, spain (size: 95 by 78 millimetres [3.7 by 3.1 in], 512 grams [18.1 oz]; main crystal: 31 millimetres [1.2 in] on edge)
    general
    categorysulfide mineral
    formula
    (repeating unit)
    fes2
    strunz classification2.eb.05a
    dana classification2.12.1.1
    crystal systemisometric
    crystal classdiploidal (m3)
    h-m symbol: (2/m 3)
    space grouppa3
    unit cella = 5.417 Å, z = 4
    identification
    formula mass119.98 g/mol
    colorpale brass-yellow reflective; tarnishes darker and iridescent
    crystal habitcubic, faces may be striated, but also frequently octahedral and pyritohedron. often inter-grown, massive, radiated, granular, globular, and stalactitic.
    twinningpenetration and contact twinning
    cleavageindistinct on {001}; partings on {011} and {111}
    fracturevery uneven, sometimes conchoidal
    tenacitybrittle
    mohs scale hardness6–6.5
    lustermetallic, glistening
    streakgreenish-black to brownish-black
    diaphaneityopaque
    specific gravity4.95–5.10
    density4.8–5 g/cm3
    fusibility2.5–3 to a magnetic globule
    solubilityinsoluble in water
    other characteristicsparamagnetic
    references[1][2][3][4]

    the mineral pyrite (t/),[5] or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula fes2 (iron(ii) disulfide). pyrite is considered the most common form of sulfide minerals.

    pyrite's metallic luster and pale brass-yellow hue give it a superficial resemblance to gold, hence the well-known nickname of fool's gold. the color has also led to the nicknames brass, brazzle, and brazil, primarily used to refer to pyrite found in coal.[6][7]

    the name pyrite is derived from the greek πυρίτης (pyritēs), "of fire" or "in fire",[8] in turn from πύρ (pyr), "fire".[9] in ancient roman times, this name was applied to several types of stone that would create sparks when struck against steel; pliny the elder described one of them as being brassy, almost certainly a reference to what we now call pyrite.[10]

    by georgius agricola's time, c. 1550, the term had become a generic term for all of the sulfide minerals.[11]

    pyrite under normal and polarized light

    pyrite is usually found associated with other sulfides or oxides in quartz veins, sedimentary rock, and metamorphic rock, as well as in coal beds and as a replacement mineral in fossils, but has also been identified in the sclerites of scaly-foot gastropods.[12] despite being nicknamed fool's gold, pyrite is sometimes found in association with small quantities of gold. a substantial proportion of the gold is "invisible gold" incorporated into the pyrite (see carlin-type gold deposit). it has been suggested that the presence of both gold and arsenic is a case of coupled substitution but as of 1997 the chemical state of the gold remained controversial.[13]

  • uses
  • formal oxidation states for pyrite, marcasite, and arsenopyrite
  • crystallography
  • crystal habit
  • varieties
  • distinguishing similar minerals
  • hazards
  • pyritised fossils
  • images
  • references
  • further reading
  • external links

Pyrite
2780M-pyrite1.jpg
Pyrite cubic crystals on marl from Navajún, La Rioja, Spain (size: 95 by 78 millimetres [3.7 by 3.1 in], 512 grams [18.1 oz]; main crystal: 31 millimetres [1.2 in] on edge)
General
CategorySulfide mineral
Formula
(repeating unit)
FeS2
Strunz classification2.EB.05a
Dana classification2.12.1.1
Crystal systemIsometric
Crystal classDiploidal (m3)
H-M symbol: (2/m 3)
Space groupPa3
Unit cella = 5.417 Å, Z = 4
Identification
Formula mass119.98 g/mol
ColorPale brass-yellow reflective; tarnishes darker and iridescent
Crystal habitCubic, faces may be striated, but also frequently octahedral and pyritohedron. Often inter-grown, massive, radiated, granular, globular, and stalactitic.
TwinningPenetration and contact twinning
CleavageIndistinct on {001}; partings on {011} and {111}
FractureVery uneven, sometimes conchoidal
TenacityBrittle
Mohs scale hardness6–6.5
LusterMetallic, glistening
StreakGreenish-black to brownish-black
DiaphaneityOpaque
Specific gravity4.95–5.10
Density4.8–5 g/cm3
Fusibility2.5–3 to a magnetic globule
SolubilityInsoluble in water
Other characteristicsparamagnetic
References[1][2][3][4]

The mineral pyrite (t/),[5] or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula FeS2 (iron(II) disulfide). Pyrite is considered the most common form of sulfide minerals.

Pyrite's metallic luster and pale brass-yellow hue give it a superficial resemblance to gold, hence the well-known nickname of fool's gold. The color has also led to the nicknames brass, brazzle, and Brazil, primarily used to refer to pyrite found in coal.[6][7]

The name pyrite is derived from the Greek πυρίτης (pyritēs), "of fire" or "in fire",[8] in turn from πύρ (pyr), "fire".[9] In ancient Roman times, this name was applied to several types of stone that would create sparks when struck against steel; Pliny the Elder described one of them as being brassy, almost certainly a reference to what we now call pyrite.[10]

By Georgius Agricola's time, c. 1550, the term had become a generic term for all of the sulfide minerals.[11]

Pyrite under normal and polarized light

Pyrite is usually found associated with other sulfides or oxides in quartz veins, sedimentary rock, and metamorphic rock, as well as in coal beds and as a replacement mineral in fossils, but has also been identified in the sclerites of scaly-foot gastropods.[12] Despite being nicknamed fool's gold, pyrite is sometimes found in association with small quantities of gold. A substantial proportion of the gold is "invisible gold" incorporated into the pyrite (see Carlin-type gold deposit). It has been suggested that the presence of both gold and arsenic is a case of coupled substitution but as of 1997 the chemical state of the gold remained controversial.[13]