Orpiment and Pyrite

ID	428
Mineral	Orpiment Pyrite
Location	Quiruvilca Mine (La Libertad Mine; ASARCO Mine) - Quiruvilca - La Libertad - Peru
Fluorescence	LW-UV: close SW-UV: close
Mindat.org	View Orpiment information at mindat.org View Pyrite information at mindat.org

ID	3021
Long ID	1:1:3021:8
Formula	`As₂S₃`
IMA Status	0 1
Other Occurrences	In low-temperature hydrothermal veins, hot springs and fumaroles; also commonly as an alteration product of arsenic minerals, especially realgar.
Diapheny	Transparent
Cleavage	Perfect {010} imperfect {100}
Tenacity	sectile
Colour	Orange-yellow to lemon-yellow
Hardness (min)	1.5
Hardness (max)	2.0
Luminescence	None
Lustre	Pearly and adamantine splendent
About the name	From Latin "aurum", gold, and "pigmentum", pigment, in allusion to its color.
Streak	Light lemon yellow
Crystal System	Monoclinic
Cleavage Type	Perfect
Morphology	Commonly in foliated columnar or fibrous aggregates, with cleavages as much as 60 cm across; may be reniform or botryoidal; also granular or powdery; rarely as prismatic crystals.
Twinning	On {100}
Thermal Behaviour	Heated in a closed tube it fuses, volatizes and gives a dark yellow sublimate.
key_elements	0
shortcode_ima	Orp

ID	3314
Long ID	1:1:3314:1
Formula	`FeS₂`
IMA Status	0 1
Other Occurrences	Common in many rock types, igneous, metamorphic and sedimentary.
Diapheny	Opaque
Cleavage	Indistinct on {001}.
Tenacity	brittle
Colour	Pale brass-yellow
Hardness (min)	6.0
Hardness (max)	6.5
About the name	Named in antiquity from the Greek "pyr" for "fire", because sparks flew from it when struck with another mineral or metal. Known to Dioscorides (~50 CE) under the name "περι υληζ ιατρικηζ" which included both pyrite and chalcopyrite.
Streak	Greenish-black
Crystal System	Isometric
Cleavage Type	Poor/Indistinct
Fracture type	Irregular/Uneven,Conchoidal
Morphology	Typically cubic or pyritohedral (pentagonal dodecahedral), sometimes octahedral and combinations are common, resulting in striated faces. Less frequently octahedral, most commonly massive, granular, and sometimes radiating, reniform, discoidal or globular.
Twinning	On [110], interpenetrating ('Iron Cross Law'). Twin axis [001] and twin plane {011}, penetration and contact twins. Twinning on (111) was described by Nicol (1904), Goldschmidt and Nicol (1904) and Gaubert (1928), all of whom considered it rare.
UV	Not fluorescent in UV
Thermal Behaviour	Heated in a closed tube gives a sublimate of sulfur and a magnetic residue.
shortcode_ima	Py
Group	Pyrite Group

Price: € 2

Dimensions: Not registered

Weight: 84 g

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