ACF diagram
ACF diagram A three-component, triangular graph used to show how metamorphic mineral assemblages vary as a function of rock composition within one metamorphic facies. Besides SiO2, the five most abundant oxides found in metamorphic rocks are Al2O3, CaO, FeO, MgO, and K2O. The three components plotted on ACF diagrams are A(Al2O3), C(CaO), and F(FeO + MgO), making the diagrams particularly useful for showing assemblage variations in metamorphosed, basic, igneous rocks and impure limestones. However, each of these components has to be modified slightly to account for the presence of other, minor components in the rock. Such modification leads to: A(Al2O3−Na2O−K2O); C (CaO − [(10/3)P2O5] − CO2); and F (FeO + MgO − Fe2O3 − TiO2). The minerals quartz and albite are assumed to be present in the rocks and are not shown on the diagram. Tielines connect minerals which coexist in equilibrium and can thus define triangular areas in which three minerals are in equilibrium in the rock, lines on which two minerals are in equilibrium in the rock, and points at which one mineral is in equilibrium in the rock (in addition to the ubiquitous quartz and albite). See AFM diagram.
More From encyclopedia.com
Iron Ores , Rocks
Rocks are composed of minerals, which are natural inorganic (nonliving) substances with specific chemical compositions and structures. A rock m… Igneous Rocks , Igneous rocks are formed by the cooling and hardening of molten magma. The word igneous comes from the Latin word igneus, meaning fire, and there are… Rock , rock1 / räk/ • n. 1. the solid mineral material forming part of the surface of the earth and other similar planets, exposed on the surface or underly… Trachyte , trachyte Fine-grained volcanic rock of the alkaline series of intermediate rocks. Trachyte is the volcanic equivalent of syenite.
trachyte gritty vol… Basic Rock , basic rock Rock with a relatively high concentration of iron, magnesium, and calcium, and with 45–53% of silica by weight. Examples include gabbro, w… Metamorphic Rocks , Metamorphic rock is rock that has changed from one type of rock into another. The word metamorphic (from Greek) means “of changing form.” Metamorphic…
You Might Also Like
NEARBY TERMS
ACF diagram