Physical Properties
Fe3O4
Color: iron-black;
Luster: metallic;
Streak: black
Magnetic: attracts magnet, but most will not
attract metal
Shape: sub-conchoidal; massive;
granular masses; octahedral
or dodecahedral crystals
Hardness: 5.5 - 6.5;
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Description
The diagnostic properties are the black streak, and attraction to a magnet. The yellow patches on this specimen are probably limonite from weathering.
Magnetite is a very widespread mineral, forming in many environments, igneous, sedimentary, and metamorphic. Often in these rocks the grains are quite small, or microscopic. It is sometimes mixed with specular hematite, confusing these two.
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