1 Formation
1.1 Formation
Variolites are a group of dark green basic igneous rocks that exhibit pale colored spots on weathered surfaces that give them a pockmarked appearance.
The banded iron layers are formed in sea water when oxygen is released by photosynthetic cyano-bacteria. The oxygen then combines with dissolved iron in ocean to form insoluble iron oxides, which precipitated out, forming a thin layer of banded iron formation on ocean floor.
1.2 Composition
1.2.1 Mineral Content
Olivine, Plagioclase, Pyroxene
Hematite, Magnetite, Quartz
1.2.2 Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Fe, Iron(III) Oxide, Silicon Dioxide
1.3 Transformation
1.3.1 Metamorphism
1.3.2 Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
Not Applicable
1.3.3 Weathering
1.3.4 Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Chemical Weathering
1.3.5 Erosion
1.3.6 Types of Erosion
Not Applicable
Coastal Erosion, Wind Erosion