Pyrite

FeS2
c 2001-2005 Mineral Data Publishing, version 1

Crystal Data: Cubic. Point Group: 2/m 3. Typically cubic, pyritohedral, octahedral, andcombinations of these and other forms, to 25 cm or more. Striated conforming to pyritohedral
symmetry; may be elongated to acicular. Commonly granular, globular, framboidal, stalactitic.
Twinning: Twin axis [001] and twin plane {011}, penetration and contact twins.
Physical Properties:
Cleavage: Indistinct on {001}; partings on {011} and {111}, indistinct.
Fracture: Conchoidal to uneven. Tenacity: Brittle. Hardness = 6–6.5 VHN = 1505–1520 (100g load). D(meas.) = 5.018 D(calc.) = 5.013 Paramagnetic; a semiconductor.
Optical Properties: Opaque. Color: Pale brass-yellow, tarnishes darker and iridescent; inpolished section creamy white. Streak: Greenish black to brownish black. Luster: Metallic,splendent. Anisotropism: Rarely.
R: (400) 38.2, (420) 40.5, (440) 42.8, (460) 45.5, (480) 48.5, (500) 51.0, (520) 52.6, (540) 53.8,(560) 54.6, (580) 55.0, (600) 55.2, (620) 55.5, (640) 56.0, (660) 56.4, (680) 56.8, (700) 57.0
Cell Data:

Space Group: P a3. a = 5.4179(11)Z=4

X-ray Powder Pattern: Synthetic.
1.6332 (100), 2.7088 (85), 2.4281 (65), 2.2118 (50), 1.9155 (40), 3.128 (35), 1.4479 (25)
Chemistry:

(1)
46.49

FeNi
Co
S

53.49

(2)
29.30
16.69
trace
53.40

(3)
33.32
0.19
13.90
52.45

(4)
46.55

53.45

Total 99.98
99.39
99.86
100.00(1) Elba, Italy; remainder 0.04% SiO2 . (2) Mill Close mine, Derbyshire, England.
(3) Gladhammar, Sweden. (4) FeS2 .
Polymorphism & Series:
Mineral Group:

Dimorphous with marcasite; forms a series with cattierite.

Pyrite group.

Occurrence: Formed under a wide variety of conditions. In hydrothermal veins as very large
bodies, as magmatic segregations, as an accessory mineral in igneous rocks, in pegmatites;in contact metamorphic deposits, also in metamorphic rocks; as diagenetic replacements insedimentary rocks.
Association: Pyrrhotite, marcasite, galena, sphalerite, arsenopyrite, chalcopyrite, many othersulfides and sulfosalts, hematite, fluorite, quartz, barite, calcite.
Distribution: The most abundant and widespread sulfide. Only a few localities for large or finecrystals can be mentioned. From Rio Marina, on Elba, and at Traversella, Piedmont, Italy. FromAmbasaguas and Navajun, Logroño Province, Spain, sculptural groups of crystals. At Aktchitao,Kazakhstan. In the USA, in the Ibex mine, Leadville, Lake Co., Colorado; in Illinois, as “suns”
at Sparta, Randolph Co.; very large crystals from the Santo Niño mine, near Duquesne, Santa
Cruz Co., Arizona. In Pennsylvania, at the French Creek mines, Chester Co., and in the Carleton
talc mine, Chester, Windsor Co., Vermont. From Butte, Silver Bow Co., Montana; at the Spruceclaim, King Co., Washington; as “bars” from the Buick mine, Bixby, Iron Co., Missouri. InPeru, from many districts, with exceptional crystals from the Quiruvilca mine, La Libertad, andHuanzala, Huanaco.
Name:

From the Greek for fire, as sparks may be struck from it.

References: (1) Palache, C., H. Berman, and C. Frondel (1944) Dana’s system of mineralogy,(7th edition), v. I, 282–290. (2) Brostigen, G. and A. Kjekshus (1969) Redetermined crystal
structure of FeS2 (pyrite). Acta Chem. Scand., 23, 2186–2188. (3) Dódony, I., M. Pósfai, and P.R.
Buseck (1996) Structural relationship between pyrite and marcasite. Amer. Mineral., 81, 119–125.
(4) (1955) NBS Circ. 539, 5, 29.
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