MINING PROPERTIES

Mining properties consist of the following (in thousands):



March 31, 2018	Palmarejo			Rochester			Silvertip		Kensington			Wharf				La Preciosa		Other			Total
Mine development	$	220,141		$	194,390		$	70,626	$	307,996		$	40,688			$	—	$	—		$	833,841
Accumulated amortization	(151,102		)	(146,245		)	—		(182,555		)	(16,456		)		—		—			(496,358		)
	69,039			48,145			70,626		125,441			24,232				—		—			337,483
Mineral interests	629,303			—			245,116		—			45,837				49,085		7,102			976,443
Accumulated amortization	(445,327		)	—			—		—			(24,655		)	—	—		(123		)	(470,105		)
	183,976			—			245,116		—			21,182				49,085		6,979			506,338
Mining properties, net	$	253,015		$	48,145		$	315,742	$	125,441		$	45,414			$	49,085	$	6,979		$	843,821



December 31, 2017	Palmarejo			Rochester			Silvertip		Kensington			Wharf				La Preciosa		Total
Mine development	$	214,383		$	193,881		$	57,214	$	298,749		$	40,618			$	—	$	804,845
Accumulated amortization	(146,598		)	(144,390		)	—		(178,632		)	(15,748		)		—		(485,368		)
	67,785			49,491			57,214		120,117			24,870				—		319,477
Mineral interests	629,303			—			245,116		—			45,837				49,085		969,341
Accumulated amortization	(435,215		)	—			—		—			(24,034		)	—	—		(459,249		)
	194,088			—			245,116		—			21,803				49,085		510,092
Mining properties, net	$	261,873		$	49,491		$	302,330	$	120,117		$	46,673			$	49,085	$	829,569

In February 2018, the Company completed the sale of Manquiri, which operates the San Bartolomé mine. Pursuant to the terms of the agreement, the Company received, among other things, a 2.0% net smelter returns royalty. Coeur estimates the value of this net smelter returns royalty to be approximately $7.1 million, which is included in Other. See Note 21 -- Discontinued Operations for additional detail.

The Silvertip mine is expected to reach commercial production in the second quarter of 2018. The determination of commercial production (or ready for intended use) is based on many factors requiring the exercise of judgment. Factors that are considered when determining if intended use has been achieved include achievement of continuous production or other output, mineral recoveries at or near expected levels, the absence of routine take-downs of the plant to address commissioning issues and fix problems, and the release of the commissioning team.

Prior to commercial production, costs related to mine development, construction of long-lived assets, and inventory are capitalized; all other costs are expensed in the period incurred. Amortization of mining properties will commence when the mine has been determined to be in commercial production.