Is there a way to choose either a symbol or color for points in a plot
according to a value in a field?

Here is what I'm trying to do:
I'm plotting depth vs porosity for some rock samples. In the file I'm using
I also have a 'zone' associated with each sample. I'd like to use that zone
column to determine either symbol shape or symbol color so I can see trends
for individual zones in the bigger plot.

Can this be done?

Thanks for the help