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A QAPF diagram is a double triangle diagram which is used to classify igneous rocks based on mineralogic composition. The acronym, QAPF, stands for "Quartz, Alkali feldspar, Plagioclase, Feldspathoid (Foid)". These are the mineral groups used for classification in QAPF diagram. Q, A, P and F percentages are normalized (recalculated so that their sum is 100%). ==Origin== QAPF diagrams were created by the International Union of Geological Sciences (IUGS): ''Subcommission on the Systematics of Igneous Rocks''〔 See for example the diagram as it appears in 〕 fostered by Albert Streckeisen (whence their alternative name: Streckeisen diagrams). Geologists worldwide accept the diagrams as a classification of igneous, especially plutonic rocks. 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「QAPF diagram」の詳細全文を読む スポンサード リンク
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