Fractional crystallization, or crystal fractionation, is the removal and segregation of early formed mineral crystals from a melt, so that the crystals cannot keep reacting with the remaining liquid. Because the crystals take particular elements with them, the residual melt becomes depleted in some components and enriched in others, and a sequence of different minerals crystallizes from it. It is one of the main processes of magmatic differentiation and one of the most important geochemical and physical processes in the crust and mantle of a rocky planet. Which mineral forms first depends on composition, pressure and water content: in mafic melts either forsterite olivine or enstatite pyroxene may precipitate, and granitic magmas can crystallize one or two feldspars. The same process is also important in the formation of sedimentary evaporite rocks.
Facts
Driving Force
Driving Force (category) Driving Force (category) Connections
Causes
Source Pegmatite (Wikipedia)
Source Pegmatite (Wikipedia)
Source Chrysoberyl (Wikipedia)
Source Elbaite (Wikipedia)
Source EBSCO Research Starters: Igneous processes, rocks, and mineral deposits
Additional Source Feldspar (Wikipedia)Compositions
Source Fluorite (Wikipedia)
Source Forsterite (Wikipedia)
Source EBSCO Research Starters: Pegmatites
Source Fractional crystallization (geology) (Wikipedia)
Additional Source Ore genesis (Wikipedia)Magmatic processes
Mica, Minerals Source EBSCO Research Starters: Igneous processes, rocks, and mineral deposits
Additional Source Mica (Wikipedia)Occurrence and production
Source Olivine (Wikipedia)
Source EBSCO Research Starters: Igneous processes, rocks, and mineral deposits
Additional Source Quartz (Wikipedia)Occurrence
Source Tourmaline (Wikipedia)
Source Spessartine (Wikipedia)
In Discipline
Source Fractional crystallization (geology) (Wikipedia)
Sources
1. Fractional crystallization (geology) (Wikipedia)
Lead
It is important in the formation of igneous rocks because it is one of the main processes of magmatic differentiation.
Igneous rocks
removal of early formed crystals from an originally homogeneous magma (for example, by gravity settling) so that these crystals are prevented from further reaction with the residual melt
View the Source2. EBSCO Research Starters: Pegmatites
EBSCO Research StartersOrigin of pegmatites
Beyond their economic value, rare-element pegmatites are of interest because they crystallize from the most evolved, or fractionated, granitic magmas in nature.
Causes: Garnet, Composition of pegmatites
They are composed predominantly of quartz, alkali feldspar, and muscovite, with minor quantities of tourmaline and garnet.
View the Source Pegmatite (Wikipedia)
Wikimedia FoundationCauses: Apatite, Petrology
A typical sequence of deposition begins with microcline and quartz, with minor schorl and garnet. This is followed by deposition of albite, lepidolite, gem tourmaline, beryl, spodumene, amblygonite, topaz, apatite, and fluorite, which may partially replace some of the minerals in the earlier zone.
Causes: Beryl, Petrology
A typical sequence of deposition begins with microcline and quartz, with minor schorl and garnet. This is followed by deposition of albite, lepidolite, gem tourmaline, beryl, spodumene, amblygonite, topaz, apatite, and fluorite, which may partially replace some of the minerals in the earlier zone.
View the Source Chrysoberyl (Wikipedia)
Causes: Chrysoberyl, OccurrenceQuote, Causes: Chrysoberyl, Occurrence
As the main magma body cools, water originally present in low concentrations became more concentrated in the molten rock because it could not be incorporated into the crystallization of solid minerals.
Elbaite (Wikipedia)
Causes: Elbaite, LeadQuote, Causes: Elbaite, Lead
Elbaite forms in igneous and metamorphic rocks and veins in association with lepidolite, microcline, and spodumene in granite pegmatites; with andalusite and biotite in schist; and with molybdenite and cassiterite in massive hydrothermal replacement deposits.
Feldspar (Wikipedia)
Wikimedia FoundationCauses: Feldspar, CompositionsQuote, Causes: Feldspar, Compositions
Calcium-rich plagioclase is the first feldspar to crystallize from cooling magma, then the plagioclase becomes increasingly sodium-rich as crystallization continues.
EBSCO Research Starters: Igneous processes, rocks, and mineral deposits
EBSCO Research StartersCauses: Feldspar, Pegmatites and hydrothermal fluids
The high water content of pegmatite fluids, some of it occurring as vapor, allows minerals such as quartz, feldspar, and mica to grow to enormous sizes, the largest of which are on the order of railway boxcars.
Causes: Mica, Pegmatites and hydrothermal fluids
The high water content of pegmatite fluids, some of it occurring as vapor, allows minerals such as quartz, feldspar, and mica to grow to enormous sizes, the largest of which are on the order of railway boxcars.
Causes: Quartz, Pegmatites and hydrothermal fluids
The high water content of pegmatite fluids, some of it occurring as vapor, allows minerals such as quartz, feldspar, and mica to grow to enormous sizes, the largest of which are on the order of railway boxcars.
View the Source Fluorite (Wikipedia)
Wikimedia FoundationCauses: Fluorite, Occurrence and miningQuote, Causes: Fluorite, Occurrence and mining
Fluorite forms as a late-crystallizing mineral in felsic igneous rocks typically through hydrothermal activity.
Forsterite (Wikipedia)
Causes: Forsterite, Geologic occurrenceQuote, Causes: Forsterite, Geologic occurrence
Due to its high melting point, olivine crystals are the first minerals to precipitate from a magmatic melt in a cumulate process, often with orthopyroxenes.
Ore genesis (Wikipedia)
Causes: Magnetite, Magmatic processesQuote, Causes: Magnetite, Magmatic processes
Chromite and magnetite are ore minerals that form in this way.
Mica (Wikipedia)
Wikimedia FoundationCauses: Mica, Occurrence and productionQuote, Causes: Mica, Occurrence and production
The most important sources of sheet mica are pegmatite deposits.
Olivine (Wikipedia)
Wikimedia FoundationCauses: Olivine, Identification and paragenesisQuote, Causes: Olivine, Identification and paragenesis
Dunite has an olivine content of over 90% and is likely a cumulate formed by olivine crystallizing and settling out of magma or a vein mineral lining magma conduits.
Quartz (Wikipedia)
Wikimedia FoundationCauses: Quartz, OccurrenceQuote, Causes: Quartz, Occurrence
Large crystals of quartz are found in magmatic pegmatites.
Tourmaline (Wikipedia)
Causes: Schorl, GeologyQuote, Causes: Schorl, Geology
Schorl and lithium-rich tourmalines are usually found in granite and granite pegmatite.
Spessartine (Wikipedia)
Causes: Spessartine, LeadQuote, Causes: Spessartine, Lead
It occurs most often in granite pegmatite and allied rock types and in certain low-grade metamorphic phyllites.
Topaz (Wikipedia)
Wikimedia FoundationCauses: Topaz, Localities and occurrenceQuote, Causes: Topaz, Localities and occurrence
It typically crystallizes in granitic pegmatites or in vapor cavities in rhyolite lava flows
Reader Challenges (0)
No disputes yet. Spotted an error or a better source? Open the first one.
Sign in to dispute this or suggest a correction.