Spherulitic magnetite (Rudnogorsk Deposit, Angara-Ilim Iron Ore District, Irkutsk Region, Siberia, Russia) 7
Magnetite is Fe3O4, a moderately common iron oxide mineral and the # 2 iron ore mineral. It has a metallic to submetallic luster, dark gray to black color and streak, a hardness of 6 on the Mohs Hardness Scale, has no cleavage, is moderately heavy for its size, and often forms octahedral crystals. Magnetite is readily identified - a magnet will stick to it, hence the name.
Seen here is a remarkable specimen of spherulitic magnetite from an iron mine at Rudnogorsk, Siberia. "Spherulitic" refers to the oolite-like, concentrically-layered, rounded to subrounded masses. The Rudnogorsk Deposit is part of the Angara-Ilim Iron Ore District, a regional cluster of magnetite-rich, metasomatized breccia pipes of explosive volcanic origin. The occurrence and geometry of magnetite bodies in the pipes is varied and complex. Magnetite mineralization occurred during emplacement of the Siberian Traps - mafic intrusions both predate and cut the breccia pipes. Siberian Traps rocks date to Permian-Triassic boundary times (~251 Ma). The major ore minerals in the district are magnesium-bearing iron oxides: magnomagnetite (MgxFe1-xFe2O4) and magnesioferrite (MgFe2O4). The light-colored material in this rock includes calcite, but 1 or more other nonmetallic minerals are also present.
Locality: mine just west of the town of Rudnogorsk, Irkutsk Region, northwest of Lake Baikal, Siberia, Russia
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Photo gallery of magnetite:
www.mindat.org/gallery.php?min=2538
Spherulitic magnetite (Rudnogorsk Deposit, Angara-Ilim Iron Ore District, Irkutsk Region, Siberia, Russia) 7
Magnetite is Fe3O4, a moderately common iron oxide mineral and the # 2 iron ore mineral. It has a metallic to submetallic luster, dark gray to black color and streak, a hardness of 6 on the Mohs Hardness Scale, has no cleavage, is moderately heavy for its size, and often forms octahedral crystals. Magnetite is readily identified - a magnet will stick to it, hence the name.
Seen here is a remarkable specimen of spherulitic magnetite from an iron mine at Rudnogorsk, Siberia. "Spherulitic" refers to the oolite-like, concentrically-layered, rounded to subrounded masses. The Rudnogorsk Deposit is part of the Angara-Ilim Iron Ore District, a regional cluster of magnetite-rich, metasomatized breccia pipes of explosive volcanic origin. The occurrence and geometry of magnetite bodies in the pipes is varied and complex. Magnetite mineralization occurred during emplacement of the Siberian Traps - mafic intrusions both predate and cut the breccia pipes. Siberian Traps rocks date to Permian-Triassic boundary times (~251 Ma). The major ore minerals in the district are magnesium-bearing iron oxides: magnomagnetite (MgxFe1-xFe2O4) and magnesioferrite (MgFe2O4). The light-colored material in this rock includes calcite, but 1 or more other nonmetallic minerals are also present.
Locality: mine just west of the town of Rudnogorsk, Irkutsk Region, northwest of Lake Baikal, Siberia, Russia
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Photo gallery of magnetite:
www.mindat.org/gallery.php?min=2538