TORONTO (miningweekly.com) – Toronto-based miner Yamana Gold on Tuesday said it had swung to a deep fourth-quarter loss after booking a $535.8-million after-tax impairment charge regarding certain of its exploration and operating properties, caused in part by lower commodity prices.

For the three months ended December 31, Yamana reported a net loss of $583.9-million, or $0.78 a share, compared with profit of $169-million, or $0.23 a share, in the same period a year earlier.

Adjusted earnings for the period totalled $36.7-million, or $0.05 a share, after adjusting for one-time and non-cash items of $620.7-million. This was lower from $197.4-million, or $0.26 a share, a year ago as lower realised metal prices, lower sales volumes, higher cash costs and an equity loss from the company's stake in the Alumbrera mine, in Argentina, impacted its finances.

Analysts had expected adjusted earnings of $0.06 a share on revenue of $483.93-million.

However, revenue for the fourth quarter fell short at $420.7-million.

Yamana said the average realised price for gold fell 25% to $1 277/oz, for silver fell 34% to $20.63/oz and for copper fell 5% to $3.37/lb.

The company had last week reported output of 1.2-million gold-equivalent ounces in 2013, below its July forecast of between 1.32-million and 1.37-million gold-equivalent ounces. However, it added that the problems that caused the shortfall were resolved by the end of the year.

Yamana, which has mines in Brazil, Mexico, Chile and Argentina, said that it took a $168.2-million after-tax impairment charge against the value of its Ernesto/Pau-a-Pique mine, in Brazil, owing to a delay in starting operations and lower metal prices.

It also booked a $182.8-million after-tax impairment charge on several exploration properties, a $55-million goodwill impairment at its Jacobina mine, in Brazil, and a $70-million after-tax impairment at Alumbrera, in which it has a 12.5% interest.

On Wednesday, Yamana’s NYSE-listed stock traded 3.13% lower at $10.20 apiece, having lost 30% in value over the past year.