In
igneous petrology, an intermediate composition refers to the
chemical composition of a rock that has 51.563
wt% SiO2 being an intermediate between
felsic and
mafic compositions. Typical intermediate rocks include
andesite
Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predomina ...
and
trachyandesite among
volcanic rock
Volcanic rocks (often shortened to volcanics in scientific contexts) are rocks formed from lava erupted from a volcano. Like all rock types, the concept of volcanic rock is artificial, and in nature volcanic rocks grade into hypabyssal and me ...
s and
diorite
Diorite ( ) is an intrusive rock, intrusive igneous rock formed by the slow cooling underground of magma (molten rock) that has a moderate content of silica and a relatively low content of alkali metals. It is Intermediate composition, inter ...
and
granodiorite among
plutonic rocks.
Geochemistry
Igneous rocks
Intermediate rocks
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