Mineral Rights

The Partnership’s mineral rights consist of the following (in thousands):



	For the Year Ended December 31, 2015
	Carrying Value		Accumulated Depletion			Net Book Value
Coal, Hard Mineral Royalty and Other	$	1,278,274	$	(432,260	)	$	846,014
VantaCore	112,700		(3,082		)	109,618
Oil and Gas	155,293		(16,898		)	138,395
Total	$	1,546,267	$	(452,240	)	$	1,094,027



	For the Year Ended December 31, 2014
	Carrying Value		Accumulated Depletion			Net Book Value
Coal, Hard Mineral Royalty and Other	$	1,680,169	$	(505,582	)	$	1,174,587
VantaCore	87,907		(482		)	87,425
Oil and Gas	560,395		(40,555		)	519,840
Total	$	2,328,471	$	(546,619	)	$	1,781,852

Depletion expense related to the Partnership’s mineral rights totaled $80.3 million, $68.6 million and $54.6 million for the year ended December 31, 2015, 2014 and 2013, respectively.

Impairment of Mineral Rights

The Partnership has developed procedures to periodically evaluate its long-lived assets for possible impairment. These procedures are performed throughout the year and consider both quantitative and qualitative information based on historic, current and future performance and are designed to identify impairment indicators. If an impairment indicator is identified, additional evaluation is performed for that asset that considers both quantitative and qualitative information. A long-lived asset is deemed impaired when the future expected undiscounted cash flows from its use and disposition is less than the assets’ carrying value. Impairment is measured based on the estimated fair value, which is primarily determined based upon the present value of the projected future cash flow compared to the assets’ carrying value. We believe our estimates of cash flows and discount rates are consistent with those of principal market participants. The inputs used by management for fair value measurements include significant inputs that are not observable in the market and thus represent a Level 3 fair value measurement for these types of assets. In addition to the evaluations discussed above, specific events such as a reduction in economically recoverable reserves or production ceasing on a property for an extended period may require that a separate impairment evaluation be completed on a significant property.

During the years ended December 31, 2015, 2014 and 2013, the Partnership identified facts and circumstances that indicated that the carrying value of certain of its mineral rights exceed future cash flows from those assets and recorded non-cash impairment expense as follows (in thousands):



	For the years ended December 31,
Impaired Asset Description	2015				2014				2013
Oil and gas properties	$	367,576	(1	)	$	—			$	—
Coal properties	257,468		(2	)	16,793		(4	)	734
Hard mineral royalty properties	43,402		(3	)	3,013		(4	)
Total	$	668,446			$	19,806			$	734

(1)

We recorded $335.7 million of oil and gas property impairment during the third quarter 2015 and $31.9 million during the fourth quarter of 2015. The fair value measurement of these impaired assets recorded at fair value were $108.0 million at the end of the reporting period. These impairments primarily resulted from declines in future expected realized commodity prices and reduced expected drilling activity on our acreage. NRP compared net capitalized costs of its oil and natural gas properties to estimated undiscounted future net cash flows. If the net capitalized cost exceeded the undiscounted future net cash flows, NRP recorded an impairment for the excess of net capitalized cost over fair value. A discounted cash flow method was used to estimate fair value. Significant inputs used to determine the fair value include estimates of: (i) oil and natural gas reserves and risk-adjusted probable and possible reserves; (ii) future commodity prices; (iii) production costs, (iv) capital expenditures, (v) production and (vi) discount rates. The underlying commodity prices embedded in the Partnership's estimated cash flows are the product of a process that begins with NYMEX forward curve pricing as of the measurement date, adjusted for estimated location and quality differentials.

(2)

We recorded $1.5 million of coal property impairment during the second quarter of 2015, $247.8 million of coal property impairment during the third quarter of 2015 and $8.2 million during the fourth quarter of 2015. The fair value measurement of these impaired assets recorded at fair value were $0.4 million at the end of the reporting period. These impairments primarily resulted from the continued deterioration and expectations of further reductions in global and domestic coal demand due to reduced global steel demand, sustained low natural gas prices, and continued regulatory pressure on the electric power generation industry. NRP compared net capitalized costs of its coal properties to estimated undiscounted future net cash flows. If the net capitalized cost exceeded the undiscounted future cash flows, NRP recorded an impairment for the excess of net capitalized cost over fair value. Significant inputs used to determine fair value include estimates of future cash flow, discount rate and useful economic life. Estimated cash flows are the product of a process that began with current realized pricing as of the measurement date and included an adjustment for risk related to the future realization of cash flows.

(3)

We recorded $43.4 million of aggregates property impairment during the third quarter of 2015. The fair value measurement of these impaired assets recorded at fair value was $0.0 million at the end of the reporting period. This impairment primarily resulted from greenfield development projects that have not performed as projected, leading to recent lease concessions on minimums and royalties combined with the continued regional market decline for certain properties. NRP compared net capitalized costs of its aggregates properties to estimated undiscounted future net cash flows. If the net capitalized cost exceeded the undiscounted cash flows, NRP recorded an impairment for the excess of net capitalized cost over fair value. A discounted cash flow model was used to estimate fair value. Significant inputs used to determine fair value include estimates of future cash flow, discount rate and useful economic life. Estimated cash flows are the product of a process that began with current realized pricing as of the measurement date and included an adjustment for risk related to the future realization of cash flows.

(4)

We recorded $16.8 million of coal property impairment and $3.0 million impairment of our aggregates properties during the fourth quarter of 2014. Management concluded certain unleased properties were impaired due primarily to the ongoing regulatory environment and continued depressed coal markets with little indications of improvement in the near term. The fair values for those unleased properties were determined for the associated reserves using Level 2 market approaches based upon recent comparable sales and Level 3 expected cash flows.