Taxable by both states:
By PA because PA residents are subject to PA income tax on all income, regardless of its source.
By WV because WV taxes non-residents on royalty payments derived from in-state natural resources.
You may claim a credit on your PA tax return for the taxes paid to WV on that income, so in effect you won't be double-taxed. Be sure to prepare your state returns as described by @MayaD.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
