Qapf Diagram. Qapf diagram for plutonic rocks. The diagram was created by the subcommission of the systematics of igneous rocks in the latter part of the 20th century.
Qapf diagram for plutonic rocks. It is made of two ternary diagram s with the corners q a p and f a p adjoined to each other along their a p edge. The qapf diagram the chapter quartz as a rock forming mineralintroduced the qapf diagram as a means to visualize and memorize the classification of igneous rocks based on their content of the minerals quartz alkali feldspar plagioclase and foids.
It is made of two ternary diagram s with the corners q a p and f a p adjoined to each other along their a p edge.
Qapf diagram represents only the normalized felsic light colored minerals part of the rock so for this illustration i avoided adding mafic dark colored minerals. The composition of the rocks are plotted into a diamond shaped coordinate system the qapf diagram also known as streckeisen diagram named after the author of the original article. The acronym qapf stands for quartz alkali feldspar plagioclase feldspathoid foid. A qapf diagram is a double ternary diagram which is used to classify igneous rocks based on mineralogic composition.
