CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Unproved properties	$ 937,395	$ 937,395
Accumulated depreciation	$ 13,000	$ 12,931
Series B Cumulative Convertible Preferred Units
Partners' equity, preferred units, outstanding (in shares)	14,711	14,711
Common units
Partners' equity - units, outstanding (in shares)	209,392	208,666

Capitalized costs of unproved properties incurred for any combination mineral interests acquisitions and other costs not previously disclosed within this table.

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The number of each class of partnership units outstanding at the balance sheet date. Units represent shares of ownership of the general, limited, and preferred partners.

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