Inventories

3 Months Ended

Mar. 31, 2021

The following table provides the components of Inventories and the estimated recoverable gold ounces therein (dollars in thousands):


	March 31, 2021			December 31, 2020
	Amount		Gold Ounces	Amount		Gold Ounces
Materials and supplies	$	6,282	—	$	6,449	—
Merrill-Crowe process plant	5,753		3,300	4,810		2,587
Carbon-in-column	2,750		1,703	299		166
Finished good (doré and off-site carbon)	4,165		2,489	1,309		710
Total	$	18,950	7,492	$	12,867	3,463

As of March 31, 2021 and December 31, 2020, in-process inventories and finished goods inventories included $0.7 million and $0.3 million, respectively of capitalized depreciation and amortization costs.

The following table summarizes Ore on leach pads and the estimated recoverable gold ounces therein (dollars in thousands):


	March 31, 2021			December 31, 2020
	Amount		Gold Ounces	Amount		Gold Ounces
Ore on leach pads, current	$	33,090	20,140	$	38,041	21,869
Ore on leach pads, non-current	9,243		5,626	7,243		4,164
Total	$	42,333	25,766	$	45,284	26,033

As of March 31, 2021 and December 31, 2020 (net of write-downs discussed below), Ore on leach pads, current included $2.4 million and $1.8 million, respectively, of capitalized depreciation and amortization costs. Additionally, as of March 31, 2021 and December 31, 2020 Ore on leach pads, non-current included $2.3 million and $0.4 million respectively, of capitalized depreciation and amortization costs.

Write-down of production inventories

The estimated recoverable gold ounces placed on the leach pads are periodically reconciled by comparing the related ore contents to the actual gold ounces recovered (metallurgical balancing). The Company did not record a Write-down of production inventories during the three months ended March 31, 2021.

During the three months ended March 31, 2020, based on metallurgical balancing results, the Company determined that 3,980 ounces of gold that had been placed on the leach pads were no longer recoverable and recognized a Write-down of production inventories on the consolidated statements of operations, which included Production costs of $6.5 million, and capitalized depreciation and amortization costs of $0.5 million. The write-offs of ounces during the three months ended March 31, 2020 were primarily due to mismanagement of the oxidation process, improper adjustments to variables in the oxidation process for changes in the ore type based on domain, and improper solution management. As a result, the Company determined it would recover less gold ounces than planned for those sections of the leach pads.

Mine site period costs

During the three months ended March 31, 2021 and 2020, the Company incurred $10.2 million and $6.6 million, respectively of Mine site period costs (which included $0.6 million and $0.5 million of capitalized depreciation and amortization, respectively) that did not qualify for allocation to the Company's production-related inventories and, therefore, were expensed as incurred. Such period costs are generally the result of recurring or significant downtime or delays, unusually high levels of repairs, inefficient operations, overuse of processing reagents, inefficient cost-volume structures, or other unusual costs and activities, and cannot be recorded to production-related inventories based on the threshold established by the calculation of the estimated net realizable value per ounce of gold, which incorporates estimated future processing, refining, and selling costs, as well as the value for by-product silver.

As a result of the Company’s decision to direct leach its run-of-mine ore, estimates for further processing leach pad ore were updated to reflect reduced reagent costs for oxidizing and rinsing ore, as well as reduced overhead and other direct costs. Had these estimated costs been applied to inventory as of December 31, 2020, the net realizable value of inventory would have been increased by approximately $2.4 million, or $0.07 per share.