| 33. | Fair value measurement |
| | | | | Fair value measurement using | | ||||||||
| | | | | Quoted prices | | Quoted prices | | Quoted prices | | ||||
| | | | | in active | | in active | | in active | | ||||
| | | | | markets | | markets | | markets | | ||||
| | | Total | | (Level 1) | | (Level 2) | | (Level 3) | | ||||
| | | US$(000) | | US$(000) | | US$(000) | | US$(000) | | ||||
| As of December 31, 2017 | | | | | | | | | | | | | |
| Assets and liabilities measured at fair value: | | | | | | | | | | | | | |
| - Embedded derivatives for concentrates sales, net | | | 7,424 | | | - | | | 7,424 | | | - | |
| - Contingent consideration liability | | | 17,570 | | | - | | | - | | | 17,570 | |
| - Hedge instruments | | | 28,705 | | | - | | | 28,705 | | | - | |
| As of December 31, 2016 | | | | | | | | | | | | | |
| Liabilities measured at fair value: | | | | | | | | | | | | | |
| - Embedded derivatives for concentrates sales, net | | | 1,524 | | | - | | | 1,524 | | | - | |
| - Contingent consideration liability | | | 19,343 | | | - | | | - | | | 19,343 | |
| - Hedge instruments | | | 3,863 | | | - | | | 3,863 | | | - | |