Intangible assets (Tables)

12 Months Ended

Dec. 31, 2018

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Schedule of Intangible Assets

	Goodwill			Mineral licenses			Other intangible assets
Cost
At December 31, 2015		32,995			55,783			—
Exchange differences		(93	)		—			—
At December 31, 2016		32,902			55,783			—
Additions		—			—			880
Disposal		—			(165	)		—
Exchange differences		(24	)		—			—
At December 31, 2017		32,878			55,618			880
Additions		—			—			—
Disposal		—			—			—
Exchange differences		90			—			—
At December 31, 2018		32,968			55,618			880
Amortisation and impairment
At December 31, 2015		(11,617	)		(17,266	)		—
Impairment		(2,930	)		(572	)		—
Amortisation		—			(1,846	)		—
At December 31, 2016		(14,547	)		(19,684	)		—
Impairment		—			(1,190	)		—
Amortisation		—			(1,504	)		—
At December 31, 2017		(14,547	)		(22,378	)		—
Impairment		(2,382	)		—			—
Amortisation		—			(1,172	)		(36	)
Disposal		—			—			—
Exchange differences		—			—			—
At December 31, 2018		(16,929	)		(23,550	)		(36	)
Net book value
At December 31, 2015		21,378			38,517			—
At December 31, 2016		18,355			36,099			—
At December 31, 2017		18,331			33,240			880
At December 31, 2018		16,039			32,068			844