OVERTURINGEN, Sweden  It was a lousy blueberry season in 2007, said Siv Wiik, 70, one of a pair of Swedish grandmothers now credited with discovering what experts say may be one of the richest gold deposits in Europe. “That year it was too cold in the spring, so there were few berries,” she said.

Berry picking is a serious business to Mrs. Wiik (pronounced VEEK), who was born in this village of 171, and her friend, Harriet Svensson, 69. For 40 years the two, widows with children and grandchildren, have explored every patch of field and forest clearing in the region, hunting for mushrooms and wild berries  blueberries, raspberries, blackberries, cloudberries.

But the women are also amateur geologists. They never leave home for a stroll in forests or fields without their geologists’ hammers, with their 30-inch handles, and their magnifying eyepieces, dangling from ribbons around their necks.

So in that terrible August when the blueberry crop failed, they decided to poke around for minerals. They went to a place called Sorkullen, far down an unpaved logging road, where trees had recently been felled, upending the earth and exposing rock to the air. Using their hammers, they cleared soil from around the stones, digging for about six hours, deeper and deeper, until they found a rock with a dull glimmer.