"Petroleum Oil & Natural Gas" but "No Minerals" Question

In Pennsylvania, if someone has only an interest in the "petroleum oil & natural gas" under a property as stated in a deed, but no mention of "minerals", do they have the right to drill into minerals (which wouldn't be owned by them) and extract oil & gas?

Wouldn't this be a concern for the marcellus and the utica shales? They are rock formations.

Also, what does PA consider a mineral?