Antofagasta (LON:ANTO) shares dropped on Wednesday morning, despite a rise in both copper and gold production in the second quarter.

Copper production rose by 6.1 percent in the second quarter to hit 163,200 tonnes, with output rising across all operations. However, the news was weighed by an 8.5 percent fall in copper output on a half year basis, due to the lower grades of the metal mined.

Gold production also saw a hefty increase of 22.9% to 39,700 in Q2, but again saw a weaker performance on a half year basis. First half output fell by 35.8 percent to 72,000 ounces. Molybdenum production fell by 9.7% to 2,800 tonnes for the quarter.

Despite the weak half-yearly performance, guidance for the full year remained unchanged. Group copper production for the full year is expected to be between 705,000 tonnes and 740,000 tonnes.

Cost guidance for the full year remained unchanged with net cash costs expected to come in at $1.35 per lb.

Shares in Antofagasta (LON:ANTO) fell by 1.40 percent to 960.80 in early trading (0857GMT).