Banded Iron Formations Flashcards
Iron and steel production is annually worth
US$400Bn
Iron and steel production is annually worth
US$400Bn
Carbon steel
Ch steel properties
Hardness, anti-corrosion
Brittle
minor types of iron deposits [4]
iron stones
magmatic iron
placer
contact metasomatic
iron stones
replace CO3 by Fe-Rich groundwaters
Magmatic Iron
e.g. mexico
Contact metasomatic
igneous intrusions and limestones
place
iron sands erosion of volcanic rocks
two major types of iron
Algoma BIF archean
Superior-type BIF MOST IMP
Carbon steel
Ch steel properties
Hardness, anti-corrosion
Brittle
minor types of iron deposits [4]
iron stones
magmatic iron
placer
contact metasomatic
iron stones
replace CO3 by Fe-Rich groundwaters
Magmatic Iron
e.g. mexico
Contact metasomatic
igneous intrusions and limestones
place
iron sands erosion of volcanic rocks
two major types of iron
Algoma BIF archean
Superior-type BIF MOST IMP
three types of formation process
a) oxygenic photosynthesis - redoxcline
b) direct biological oxidation - iron chemocline
c) UV induced oxidation - iron chemocline
BIFs alternate between
Fe-rich dark
Silica rich white/red/jasper/chert
6 stages of iron formation
○ Upwelling and hydrothermal ○ Oxidized Fe III as closer to surface ○ Changes to iron carbonates as precipitated out ○ Forms superior or alg. ○ Transport of iron as Fe2+ ○ Precipitation on oxidation to Fe3+
important iron regions
Hamersley ranges of Australia, Carajas, Brazil.
iron layers [4]
Fe-oxides – magnetite, hematite
Fe-sulfides – pyrite, pyrrhotite
Fe-carbonates – siderite
Fe-silicates – Fe-rich talc, chlorite,
