The solid solution series of the plagioclase feldspars is along the base of the triangle. The left edge of the plot represents the solid solution series of the alkali feldspars. One of the most familiar examples of a triangular plot in the Earth sciences illustrates the classification of feldspar minerals. That composition makes the rock a 'granitoid.' Another rock plots at 10% quartz, 40% alkali feldspar, and 50% plagioclase, making the rock a 'syenitoid.' One is at a composition of 50% quartz, 40% alkali feldspar, and 10% plagioclase. By this chart, rocks that contain greater than 60% quartz are known as 'quartz-rich granitoids,' those that contain between 20% and 60% quartz are known as 'granitoids.' Those that contain less than 20% quartz and are rich in alkali feldspar are known as 'syenitoids.' Other rocks are either dioritoids, gabbroids, or anorthosites. A field classification chart is shown below. In petrology, plutonic igneous rocks are classified by the relative abundance of quartz (Q), plagioclase (P), and alkali feldspar (A) in their composition. pdf document reader such as Adobe Reader. They are designed to print on a standard sheet of 8 1/2 x 11 paper. Choose the paper that will contrast with the pencil or pen color that you will be plotting with. We have two types of triangular graph paper, one with black lines and one with blue. Ternary plots are also used in genetics and game theory. The charts produced from this method of graphing are generally referred to as 'ternary plots' or 'ternary diagrams.' They are frequently used to plot the compositions of mixtures in physical chemistry, petrology, mineralogy, metallurgy and other physical sciences. This type of two-dimensional graph can be made when the sum of the three variables always adds up to a constant - usually 100% or 1. Triangular graph paper is used to graph the relationships between three variables on an equilateral triangle.

Feldspar ternary diagram