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The Mineral loellingite

Loellingite with Siderite

Loellingite, also known as Löllingite, is named after the Austrian type locality it was first described in, which is Loelling (or Lölling), Carinthia, Austria. Since the English language lacks the letter O with an umlaut, this guide uses the alternate spelling of Loellingite.

Loellingite belongs to the Loellingite group, which is a group of chemically related isomorphous minerals that are all uncommon. Other members discussed in this guide are Rammelsbergite and Safflorite.

Chemical Formula

FeAs₂

Color

Silver-white. Tarnishes dark gray.

Crystal System

Orthorhombic

Properties

Streak
Dark gray

Hardness
5 - 5.5

Transparency
Opaque

Specific Gravity
7.1 - 7.6

Luster
Metallic

Cleavage
3,1 - basal

Fracture
Uneven

Tenacity
Brittle

Other ID Marks
Gives off a garlic odor when struck or heated. (Fumes are toxic.)

Crystal Habits

Occurs as interestingly shaped prismatic crystals, as well as tabular crystals. Crystals frequently twin to form cross or star shaped aggregates. Also occurs columnar, acicular, bladed, radiating, grainy, in thin veins, massive, and as compact aggregates.

3D Crystal Atlas

Additional Information

Composition
Iron arsenate, sometimes with some nickel and cobalt. If the iron (Fe) is replaced by more than 50% nickel (Ni), the mineral is not Loellingite, but Rammelsbergite, and if it is replaced by more than 50% cobalt (Co), the mineral is Safflorite.

In Group
Sulfides; Arsenides

Striking Features
Crystal habits, gives off garlic odor when struck

Environment
In mesothermal veins associated with other sulfides, and also in limestone and less commonly in pegmatites.

Rock Type
Igneous, Sedimentary, Metamorphic

Other Names

Löllingite

Varieties

Cobaltian Loellingite

- Cobaltrich variety of Loellingite

Nickelian Loellingite

- Nickelrich variety of Loellingite

Uses

Loellingite is found together with other arsenic minerals, and is thus a minor ore of arsenic.

Noteworthy Localities

Loellingite is not a common mineral, and has been found in the following European localities: the Wolfbau Mine, Loelling, Carinthia, Austria; Carles, Asturias, Spain; the Ste Marie-aux-Mines, Alsace, France; and Dolni Bory, Moravia, Czech Republic.

Loellingite was found in Australia in Broken Hill, New South Wales, in highly lustrous crystals. A recent find of Loellingite, in exceptionally large crystals, is the Huanggang Mine, Inner Mongolia, China.

In the U.S., Loellingite was found in Franklin and Ogdensburg, Sussex Co., New Jersey; Amity and Warwick, Orange Co., New York; Center Strafford, Strafford Co., New Hampshire; near Auburn, Androscoggin Co., Maine; and Mt Mica, Paris, Oxford Co., Maine. In Canada, it was found in the Cobalt area, Timiskaming District, Ontario.

Common Mineral Associations

Arsenopyrite, Siderite, Calcite, Chloanthite, Magnetite, Galena, Sphalerite, Pyrite

Distingushing Similar Minerals

Arsenopyrite - Very hard to distinguish without complex analysis.
Skutterudite, Safflorite, and Rammelsbergite - Indistinguishable without x-ray analysis. However, Safflorite and Rammelsbergite occur in different environments than Loellingite.
Pyrite, Marcasite, and Pyrhottite - Occur in different crystals, more yellow in color.
Cobaltite - Occurs in different crystals.