# How to determine the phases in a complex phase diagram?

In my school notes, we have the following phase diagram that shows an example of how complex things can get when we have intermediate phases. I tried filling in phases, but I have no idea how to check if I am doing a good job or not. What is the mechanism to determine the phases starting with a diagram like this? This is a question I have made for myself, NOT homework.

• Pretty close, but you have a line compound near 60 wt.% that you haven’t identified. – Jon Custer Mar 28 '18 at 18:18
• That is where I had more trouble working. What is a line compound? It made sense for there to be another phase in between $\beta$ and $\epsilon$, but I never thought a whole compound could be represented by a line. Would you mind explaining further? Thank you! – Bee Mar 28 '18 at 19:26
• A line compound is one that has a single composition. For example, Al2O3 does not have any range of composition. – Jon Custer Mar 28 '18 at 21:39