Itabirite, also known as banded-quartz

hematite Hematite (), also spelled as haematite, is a common iron oxide compound with the formula, Fe2O3 and is widely found in rocks and soils. Hematite crystals belong to the rhombohedral lattice system which is designated the alpha polymorph of . ...

and hematite

schist Schist ( ) is a medium-grained metamorphic rock showing pronounced schistosity. This means that the rock is composed of mineral grains easily seen with a low-power hand lens, oriented in such a way that the rock is easily split into thin flakes o ...

, is a

laminated Lamination is the technique/process of manufacturing a material in multiple layers, so that the composite material achieves improved strength, stability, sound insulation, appearance, or other properties from the use of the differing materia ...

metamorphosed Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causin ...

oxide-

facies In geology, a facies ( , ; same pronunciation and spelling in the plural) is a body of rock with specified characteristics, which can be any observable attribute of rocks (such as their overall appearance, composition, or condition of formatio ...

iron formation in which the original

chert Chert () is a hard, fine-grained sedimentary rock composed of microcrystalline or cryptocrystalline quartz, the mineral form of silicon dioxide (SiO2). Chert is characteristically of biological origin, but may also occur inorganically as a prec ...

jasper Jasper, an aggregate of microgranular quartz and/or cryptocrystalline chalcedony and other mineral phases,Kostov, R. I. 2010. Review on the mineralogical systematics of jasper and related rocks. – Archaeometry Workshop, 7, 3, 209-213PDF/ref> ...

bands have been recrystallized into megascopically distinguishable grains of

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical form ...

and the iron is present as thin layers of hematite,

magnetite Magnetite is a mineral and one of the main iron ores, with the chemical formula Fe2+Fe3+2O4. It is one of the oxides of iron, and is ferrimagnetic; it is attracted to a magnet and can be magnetized to become a permanent magnet itself. With the ...

, or ''martite'' (

pseudomorph In mineralogy, a pseudomorph is a mineral or mineral compound that appears in an atypical form (crystal system), resulting from a substitution process in which the appearance and dimensions remain constant, but the original mineral is replaced by ...

s of hematite after magnetite).US Bureau of Mines Dictionary of Mining, Mineral, and Related Terms. Accessed 12 December 2010
The term was originally applied in

Itabirito Itabirito is a municipality in the Minas Gerais state of Brazil. Its population is estimated to have 52,446 people in 2020. The city belongs to the mesoregion Metropolitan of Belo Horizonte and to the microregion of Ouro Preto. The municipality co ...

(Pico de Itabirito), in the state of

Minas Gerais Minas Gerais () is a state in Southeastern Brazil. It ranks as the second most populous, the third by gross domestic product (GDP), and the fourth largest by area in the country. The state's capital and largest city, Belo Horizonte (literally ...

and southern part of

Belo Horizonte Belo Horizonte (, ; ) is the sixth-largest city in Brazil, with a population around 2.7 million and with a metropolitan area of 6 million people. It is the 13th-largest city in South America and the 18th-largest in the Americas. The metropol ...

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

, to a high-grade, massive specular hematite ore (66% iron) associated with a

schistose Schist ( ) is a medium-grained metamorphic rock showing pronounced schistosity. This means that the rock is composed of mineral grains easily seen with a low-power hand lens, oriented in such a way that the rock is easily split into thin flakes o ...

rock composed of granular quartz and scaly hematite. The term is now widely used outside Brazil.Carlos Alberto Rosière et al.: ''Itabira Peak, State of Minas Gerais. Geographic, historical and structural landmark of the Quadrilátero Ferrífero''. In: Sítios Geológicos e Paleontológicos do Brasil (SIGEP) 042, 2005

References

Geology of Brazil Iron minerals Metamorphic rocks {{mineral-stub