Kilauea Lava Lake

Figure 6.00. Aerial photograph of active lava lake. Hale maʻumaʻu Crater at the summit of Kīlauea volcano on 27 July 2016. Click on the photo to see a larger version with more infomation.

Ternary Eutectic Diagrams

6.1 Overview

Adding a third chemical component to a magma leads to some qualitatively different features upon crystallization. These features are revealed by examining ternary (three-component) equilibrium diagrams for simple igneous systems. Concepts that are developed in this chapter include:
  • saturation of ternary liquids
  • ternary lever rule
  • ternary liquidus surfaces
  • ternary cotectic curves
  • ternary reaction curves
  • ternary eutectic points
Concepts that are used in this chapter, include chemical equilibrium, composition axes, ternary diagrams, saturation, eutectic point, peritectic point, and the lever rule.