Harker diagram
plot of oxides of elements found in rocks vs. silica content
In geology, a Harker diagram, a type of a variation diagram, is a plot of oxides of elements found in rocks vs. their silica content.
Typically, in igneous rocks, as silica content increases, iron, magnesium, calcium and titanium oxides decrease in abundance. In contrast, oxides of alkali metals such as Na2O and K2O increase in abundance as silica content increases, while aluminium and phosphorus oxides tend to increase in abundance and then fall.
Such diagrams are used as a visualization tool for exploring the fractionation history of igneous rocks.
“Harker diagram” enters the record as plot of oxides of elements found in rocks vs. silica content. Crown Archives preserves that source wording while asking what Harker, diagram and plot can confirm, complicate or overturn.
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This entry incorporates text from “Harker diagram” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.