Iron Leads to Gold

Could the humble iron make us rich? Swedish researchers tend to say yes, as they linked iron ore deposits to gold deposits.

In northern Sweden, iron ore has been extracted for many centuries and today it is still mined from two places-Kirunavaara and Malmberget. Kirunavaara site has also given its name to the Kiruna apatite iron ore, an international denomination.

Around the world, in countries like Chile and Sweden, copper and gold have been sometimes discovered close to certain iron ores. This fact made researchers from Luleå University of Technology in Sweden to suspect a link between these "big three": they could have emerged at the same time, deep down in the earth crust.

At Tjärrojåkka, about 50 km (30 mi) west southwest of Kiruna, the Geological Survey of Sweden (SGU) discovered a copper/gold mineralization in the '70s, while in the mid 1960s it had found nearby an iron deposit.

The copper-golf deposit was too small to be economically profitable, but all the data gathered from the drill cores and their analysis results showed this is the best Swedish example of proximate iron and copper/gold finds.

"The point of departure for my studies has been to examine whether iron ores and copper/gold ores can be formed during one and the same ore-formation event, and to identify properties in them that can be used for prospecting both in Sweden and abroad," said Åsa Edfelt, who investigated the deposits in her doctoral dissertation.

"I have carried out comparative studies of age, chemical characteristics of minerals, formation temperatures, and the consistency of the ore-forming solutions in these two finds at Tjärrojåkka and found that they were formed during one and the same event."

Edfelt has also discovered that the mineral apatite could be used to track down what types of iron ore lead to copper. This research could be important for the prospecting market worldwide.

Only in northern Sweden, there are 50 iron deposits that could be prospected for copper and gold.