The differences between them are striking. Eagle shows the highest degree of thermo-metamorphism of our samples, and Sahara has the least. The number refers to the degree of thermo-metamorphism, with 7 being the highest (totally melted). H/L refers to them containing relatively high iron or low iron. Wikimedia Commons has media related to QAPF diagram.'E' designates that they are enstatite chondrites. Classification of Igneous Rocks - IUGS Classification, Geological Sciences Department - Cal Poly Pomona, archived from the original on 30 September 2011.Igneous Rocks: A Classification and Glossary of TermsВ : Recommendations of International Union of Geological Sciences Subcommission on the Systematics of Igneous Rocks.

Neues Jahrbuch fГјr Mineralogie, Abhandlungen, Vol. Classification and Nomenclature of Volcanic Rocks, Lamprophyres, Carbonatites and Melilite Rocks. IUGS Subcommission on the Systematics of Igneous Rocks. Cambridge, UK: Cambridge University Press. Principles of igneous and metamorphic petrology (2ndВ ed.). British Geological Survey: Rock Classification Scheme. ^ 'Rock Classification Scheme - Vol 1 - Igneous' (PDF).'Classification and nomenclature of plutonic rocks recommendations of the IUGS subcommission on the systematics of Igneous Rocks'. The QAPF diagram is not used for all plutonic rocks ultramafic plutonic rocks are the most important group that have separate classification diagrams. This diagram makes no distinction between rock types of the same chemical composition in QAPF, but different chemical compositions with respect to other minerals (such as gabbro, diorite, and anorthosite). For example: a plutonic rock that contains no alkali feldspar and no feldspathoids, but contains many pyroxenes (unlabeled in QAPF diagram), plagioclase-feldspar, and few quartz grains is probably gabbro (located at the right edge of the diagram, near P). To use this classification method, the concentration (the mode) of these minerals must be determined and normalized to 100%. The QAPF diagram is composed of two ternary plots (QAP and FAP) joined along one side. Other minerals may occur in samples, but they are not utilized by this classification method. F and Q cannot form in plutonic rocks simultaneously due to the difference in their respective silica contents. These minerals are quartz (Q), Alkali feldspars (A), plagioclase feldspars (P), and feldspathoids (F). The QAPF diagram utilizes four minerals, or mineral groups, to classify igneous rocks. QAPF diagrams are also not used if mafic minerals make up more than 90% of the rock composition (for example: peridotites and pyroxenites).ДЄn exact name can be given only if the mineralogical composition is known, which cannot be determined in the field. TAS is also used if volcanic rock contains volcanic glass (such as obsidian). QAPF diagrams are not used to classify pyroclastic rocks or volcanic rocks if modal mineralogical composition is not determined, instead the TAS classification (Total-Alkali-Silica) is used. QAPF diagrams are mostly used to classify plutonic rocks ( phaneritic rocks), but are also used to classify volcanic rocks if modal mineralogical compositions have been determined. Geologists worldwide accept the diagrams as a classification of igneous, especially plutonic rocks.

QAPF diagrams were created by the International Union of Geological Sciences (IUGS): Subcommission on the Systematics of Igneous Rocks ДЇostered by Albert Streckeisen (whence their alternative name: Streckeisen diagrams).

Enstatite ternary diagram