how do I know what my pool is made of?

[sydneyfnp]

This may sound dumb, but I have no idea how to tell what our pool is made of. It's an older in-ground type. I know there is no liner, but not sure how to tell if it's plaster or concrete... Have seen people referring to gunnite (sp?) - not sure what that is. The pool has slanting sides, rough texture.

[mr_clean]

Its a plaster pool

What is plaster and gunite?
Plaster is the coating over the gunite pool shell that is made of crushed white marble dust. Gunite is the concrete shell of the pool with rebar enforcement.

If it was a fiberglass pool it would be smooth