Classic chemistry, geology yields Alaska’s first diamond prospect

Patricia Jones, Petroleum News contributing writer

Diamonds found in drilling on the Shulin Lake property near Talkeetna last summer — the first known discovery of a bedrock source for such gemstones in Alaska — upended long-established geological models of the state.

“Alaska’s geology is not favorable for kimberlite pipes such as those in … Northwest Territories,” said Curt Freeman, a Fairbanks-based consulting geologist.

Shulin Lake partners Golconda Resources Ltd. and Shear Minerals Ltd. used classic chemical analysis and prospecting techniques for the discovery, said David Szumigala, geologist at the Division of Geological and Geophysical Surveys.

Geologists panning for gold found concentrations of minerals commonly found with diamonds, he said. “Lab results showed that the composition of those minerals was the right signature for diamonds.”

Specific drill targets were identified with both state-funded and company-acquired airborne geophysical mapping, Szumigala said. Core samples drilled last summer yielded 15 micro-diamonds and one macro-diamond.

“To drill and find any diamonds is a success,” Szumigala said. “Where Shulin Lake is and how it fits into the known geological model is interesting. It’s sort of an unusual place for diamonds.”

Assessing the quality and size of the gemstone deposit is the next step, he said.

“Many diamond deposits are not mined because they contain industrial grade diamonds that are not valuable enough,” Szumigala said.

The geological context of the diamond discovery “continues to be discussed within the Alaska exploration community,” he noted in an overview of Alaska’s Mineral Industry released by the state earlier this year.