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Classic Magnetite Octahedron on Matrix

The Mineral magnetite

Magnetite is best known for its property of being strongly attracted to magnets. Some forms of Magnetite from specific localities are in fact themselves magnets. Commonly known as Lodestone, this magnetic form of Magnetite is the only mineral that is a natural magnet. Due to the magnetism of Lodestone, small iron particles are often found clinging to its surfaces. (Some dealers may even intentionally place metallic filings on a Lodestone to demonstrate its magnetism.)

Magnetite may form a yellow-brown rust coating if washed or kept in a moist area. If a specimen is washed, it should be dried to prevent rusting. Rust can easily be removed by soaking the Magnetite in a rust-removing solvent such as Iron Out.

The mineral Hematite is known to form pseudomorphs over Magnetite. Such pseudomorphs are commonly known as Martite, and their appearance may be very similar to regular Magnetite. However, they differ from Magnetite in that they are only weakly attracted to magnetic fields, and have a reddish-brown streak.
Chemical Formula Fe2+Fe3+2O4
Composition Iron oxide. May contain several different elemental impurities partially replacing both the first and the second iron.
Variable Formula (Fe,Mn,Mg,Zn,Ni)2+(Fe,Al,Cr,Mn)3+2O4
Color Dark gray to black
Streak Black
Hardness 5.5 - 6.5
Crystal System Isometric
3D Crystal Atlas
(Click for animated model) 
Crystal Forms
and Aggregates
Crystals are usually octahedral, and they may be very well-formed. Less commonly dodecahedral. Crystals may exhibit interesting combinations of octahedral and dodecahedral faces. Spinel twinning is an occasional habit, and an unusual cubic form is well-known from one specific locality. Crystals may be striated, and some octahedral crystals contain layer growths. Also drusy, grainy, in veins, as large embedded grains, as rounded crystals, and massive.
Transparency Opaque
Specific Gravity 4.9 - 5.2
Luster Metallic
Cleavage None. May exhibit parting.
Fracture Subconchoidal to uneven
Tenacity Brittle
Other ID Marks Is ferromagnetic, meaning it is strongly attracted to magnetic fields.
In Group Oxides; Multiple Oxides
Striking Features Strong attraction to magnets, hardness, and streak.
Environment Occurs in igneous rock such as diabase, as well as contact and regional metamorphic rocks and in hydrothermal replacement deposits.
Rock Type Igneous, Metamorphic
Popularity (1-4) 2
Prevalence (1-3) 1
Demand (1-3) 1

Magnetite AUCTIONS

 -  Chromiumrich variety of Magnetite.
 -  Massive, magnetic variety of Magnetite that acts as a natural magnet.
 -  Banded formation known as taconite - the primary Iron ore known primarily from the Mesabi Range in Minnesota composed of dark, metallic-lustered layers of Magnetite combined red chert in between.
 -  Titanium-rich variety of Magnetite.

Magnetite is an important ore of iron. Well formed crystals are popular among mineral collectors, and the magnetic Lodestone variety is frequently sold in hobby shops to amateur collectors. Magnetite is also of significant interest to the science community due to its strong magnetic properties.

Magnetite is a common mineral. Much commercially-mined Magnetite is of massive form and lacks interest to collectors. Due to the worldwide prevalence of Magnetite, only significant or historical localities are mentioned here.

Single octahedral Magnetite crystals, often in matrix, are well known from Binn Tal, Wallis, Switzerland. These crystals sometimes have characteristic layer growths or triangular striations. Some of the largest Magnetite deposits exist in northern Sweden, with very good crystals having come from Nordmark. Well-formed crystals come from the Kovdor Mine in the Kola Peninsula, Russia; and heavily striated crystals with growth layers come from Parachinar, Pakistan. In South America, highly lustrous and perfectly formed octahedral Magnetite crystals are mined at Cerro Huanaquino, Potosi, Bolivia. 

In the U.S., large Magnetite masses, sometimes with partial or full octahedral faces, have come from Franklin and Ogdensburg, Sussex Co., New Jersey; and perfect octahedral crystals from Chester, Windsor Co., Vermont. Lustrous cubic crystals were found in Balmat, St. Lawrence Co., New York, producing a unique habit of Magnetite unlike any other. The French Creek Mine, St. Peters, Chester Co., Pennsylvania has produced some large octahedrons. The magnetic variety Lodestone comes from the Iron Springs area (Dixie National Forest,) Washington/Iron counties, Utah; and from Magnet Cove, Hot Spring Co., Arkansas.
There are several classic Magnetite localities on the East Coast of the United States, which have been out of production for many decades or even centuries. Unique dodecahedral crystals, often with rounded corners, were at one time mined at the old Tilly Foster Mine, Brewster, Putnam Co., New York. Massive and poorly crystallized Magnetite was once mined in abundance in the 19th-century iron mines in the Ramapo Mountains, Sterling Forest, and Hudson Highlands region of Orange/Rockland Counties, New York., as well as the Jersey Highlands of Passaic Co., New Jersey. Laurel Hill (Snake Hill) in Secaucus, Hudson Co., New Jersey has produced excellent, isolated octahedral crystals in a diabase matrix.

Calcite, Hornblende, Biotite, Phlogopite, Talc, Pyrite, Epidote, Hematite, Apatite, Almandine, Chlorite

Franklinite - Only weakly attracted to magnetic fields.
Spinel - Not attracted to magnetic fields, has a white streak.
Ilmenite - Lighter streak.
Chromite - Has a brownish streak.
Hematite pseudomorph after Magnetite - Has a weaker magnetic attraction.

magnetite PHOTOS
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