1 Formation
1.1 Formation
Porphyry is formed in two stages: the magma cools slowly deep within the crust or the magma is cools rapidly as it erupts from a volcano, creating small grains that are usually invisible to naked eye.
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
Biotite, Chert, Feldspar, Garnet, Graphite, Quartz, Silica
Hematite, Magnetite, Quartz
1.2.2 Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, Potassium Oxide, MgO, Sodium Oxide, 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, Not Registered
Chemical Weathering
1.3.5 Erosion
1.3.6 Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
Coastal Erosion, Wind Erosion