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Minerals and rocks are sometimes loosely classified according to composition. The various compositions are shown in this diagram. They range from acidic or siliceous (high silica content) through basic or mafic (high content of heavy elements such as iron or of elements with chemical affinity for iron) to ultrabasic or ultramafic (very rich in heavy elements and low in silica).
The diagram shows that Olivene and Pyroxene can be called ultrabasic minerals, Calicum-feldspar (plagioclase), Amphibole and Biotite (a mica) can be called Basic minerals, orthoclase is an intermediate mineral, and Quartz and Muscovite (another form of mica) can be called Acidic.
A very rough rule of thumb is that the darker or denser the rock type, the more basic it is. In a planet that has been at least partially molten, crustal minerals and rocks tend to be siliceous, erupted lavas tend to be basic, and deep-seated minerals and rocks tend to be ultrabasic.
Go to a listing of Rocks by mineral group
Minerals and rocks are sometimes loosely classified according to composition. The various compositions are shown in this diagram. They range from acidic or siliceous (high silica content) through basic or mafic (high content of heavy elements such as iron or of elements with chemical affinity for iron) to ultrabasic or ultramafic (very rich in heavy elements and low in silica).
The diagram shows that Olivene and Pyroxene can be called ultrabasic minerals, Calicum-feldspar (plagioclase), Amphibole and Biotite (a mica) can be called Basic minerals, orthoclase is an intermediate mineral, and Quartz and Muscovite (another form of mica) can be called Acidic.
A very rough rule of thumb is that the darker or denser the rock type, the more basic it is. In a planet that has been at least partially molten, crustal minerals and rocks tend to be siliceous, erupted lavas tend to be basic, and deep-seated minerals and rocks tend to be ultrabasic.
Go to a listing of Rocks by mineral group
Not applicable at this reading level.
Go to a listing of Rocks by mineral group
