Yes you get stepped up basis.
But the mineral produce income and in the interceding years depletion was claim. To my understanding you must recapture that depletion. From the 4797 instructions:
“Disposition of Depreciable Property Not Used in
Trade or Business
Generally, gain from the sale or exchange of depreciable
property not used in a trade or business but held for
investment or for use in a not-for-profit activity is capital
gain. Generally, the gain is reported on Form 8949 and
Schedule D. However, part of the gain on the sale or
exchange of the depreciable property may have to be
recaptured as ordinary income on Form 4797. Use Part III
of Form 4797 to figure the amount of ordinary income
recapture. The recapture amount is included on line 31
(and line 13) of Form 4797. See the instructions for Part III.
If the total gain for the depreciable property is more than
the recapture amount, the excess is reported on Form
8949. On Form 8949, enter “From Form 4797” in column
(a) of Part I (if the transaction is short term) or Part II (if the
transaction is long term), and skip columns (b) and (c). In
column (d), enter the excess of the total gain over the
recapture amount. Leave columns (e) through (g) blank
and complete column (h). If you invested this gain into a
QOF and intend to elect the temporary deferral of the
gain, see the Instructions for Form 8949; Form 8997, Initial
and Annual Statement of Qualified Opportunity Fund
(QOF) Investments, and its instructions; and the
instructions for the applicable Schedule D.”
