Loellingite

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title: "Loellingite" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["iron-minerals", "arsenide-minerals", "orthorhombic-minerals", "minerals-in-space-group-58"] description: "Iron arsenide mineral" topic_path: "general/iron-minerals" source: "https://en.wikipedia.org/wiki/Loellingite" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Iron arsenide mineral ::

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

Field	Value
name	Loellingite
image	Lollingite-177962.jpg
caption	Sharp, lustrous loellingite (and/or arsenopyrite) crystals to 4 mm on gossan matrix. Locality: Broken Hill Ore Deposit, New South Wales, Australia. Size: 2.4 × 2.2 × 2.0 cm.
category	Arsenide mineral
formula	FeAs2
IMAsymbol	Lö
strunz	2.EB.15a
system	Orthorhombic
class	Dipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)
symmetry	Pnnm
unit cell	a = 5.16, b = 5.93
c = 3.05 [Å]; Z = 2
color	Steel grey to silvery white
habit	Prismatic to pyramidal crystals, massive
twinning	On {001}, possibly trillings, polysynthetic on {101}
cleavage	Rare, distinct on {010}, {101}
fracture	Uneven
mohs	5–5.5
luster	Metallic
streak	Grayish black
gravity	7.1–7.5
opticalprop	Distinctly anisotropic in reflected light
references
::

| name = Loellingite | boxwidth = | boxbgcolor = | image = Lollingite-177962.jpg | imagesize = | alt = | caption = Sharp, lustrous loellingite (and/or arsenopyrite) crystals to 4 mm on gossan matrix. Locality: Broken Hill Ore Deposit, New South Wales, Australia. Size: 2.4 × 2.2 × 2.0 cm. | category = Arsenide mineral | formula = FeAs2 | IMAsymbol = Lö | molweight = | strunz = 2.EB.15a | dana = | system = Orthorhombic | class = Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m) | symmetry = Pnnm | unit cell = a = 5.16, b = 5.93 c = 3.05 [Å]; Z = 2 | color = Steel grey to silvery white | colour = | habit = Prismatic to pyramidal crystals, massive | twinning = On {001}, possibly trillings, polysynthetic on {101} | cleavage = Rare, distinct on {010}, {101} | fracture = Uneven | tenacity = | mohs = 5–5.5 | luster = Metallic | streak = Grayish black | diaphaneity = | gravity = 7.1–7.5 | density = | polish = | opticalprop = Distinctly anisotropic in reflected light | refractive = | birefringence = | pleochroism = | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | references = Loellingite, also spelled löllingite, is an iron arsenide mineral with formula FeAs2. It is often found associated with arsenopyrite (FeAsS) from which it is hard to distinguish. Cobalt, nickel and sulfur substitute in the structure. The orthorhombic lollingite group includes the nickel iron arsenide rammelsbergite and the cobalt iron arsenide safflorite. Leucopyrite is an old synonym for loellingite.

It forms opaque silvery white orthorhombic prismatic crystals often exhibiting crystal twinning. It also occurs in anhedral masses and tarnishes on exposure to air. It has a Mohs hardness of 5.5 to 6 and a quite high specific gravity of 7.1 to 7.5. It becomes magnetic after heating.

Loellingite was first described in 1845 at the Lölling district in Carinthia, Austria, for which it was named.

It occurs in mesothermal ore deposits associated with skutterudite, native bismuth, nickeline, nickel-skutterudite, siderite and calcite. It has also been reported from pegmatites.

::figure[src="https://upload.wikimedia.org/wikipedia/commons/a/af/Lollingite-266955.jpg" caption="Loellingite from Franklin-Sterling (size: 10.4 × 7.0 × 6.8 cm)"] ::

References

References

1. Warr, L.N.. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine.
2. [http://www.mindat.org/min-2426.html Mindat]
3. [http://webmineral.com/data/Lollingite.shtml Webmineral]
4. [http://rruff.geo.arizona.edu/doclib/hom/lollingite.pdf Handbook of Mineralogy]

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