The composition for each of these points is shown below. Also observe that the ternary diagram is read counter clockwise. Note that the heavy red lines are not included in this final triangle. The sum result is the ternary diagram to the right with all the scales present. We construct the percent abundance scale for C by rotating the heavy red scale line another 120 degrees so that it runs from the left side of the triangle to the lower right corner, and the percent scale lines and percent abundance numbers rotate with it. Point C is at the lower right apex of the triangle. These lines are projected out to the left and bottom sides of the triangle, and the percent scale for B laid out along the left side. The right side of the triangle now becomes the base line for the percent scale for B, and a series of red lines have been drawn parallel to the triangle's right side to mark off the percentages. We construct a percent abundance scale for B by rotating the heavy red scale line 120 degrees counter clock wise so that it runs from the right side of the triangle to the lower left corner. Point B is at the lower left apex of the triangle. In the final ternary diagram the red vertical arrow is removed. To be complete the hoirizontal lines also extend to the left until they contact the left side of the imaginary triangle, but no percent abundances are written there. By doing this the right side of the triangle becomes the scale for percent abundance of A. The lines are projected out to the right of the red arrow line just as far as where the imaginary side of the triangle will be, and their percentage abundances written along the right side of the triangle. The horizontal lines that represent various percents of A can be of any length since they run parallel to the base line and remain the same distance from the bottom and top of the triangle. Any other percentage can be indicated by a line appropriately located along the line between 0% and 100%, as shown by the numbers off to the right. A horizontal bar at the bottom of the line (farthest from A) represents 0% of A.

A point plotted at the top of the vertical line nearest A indicates 100% A. Along this line is indicated percent of A. Point A is at the top of the heavy vertical red line (arrow). The drawing to the left has only the skeleton of the triangle present as we concentrate on point A. We are going to take the diagram apart to see how it works. For the moment they are labeled A, B, and C. A ternary diagram is a triangle, with each of the three apexes representing a composition, such as sandstone, shale, and limestone.

Marble index minerals ternary diagram