Denison hits high-grade unconformity uranium mineralisation at Gryphon

VANCOUVER (miningweekly.com) – Uranium explorer Denison Mines has, for the first time, found unconformity uranium mineralisation at its Gryphon deposit, on its 60%-owned Wheeler River project, in the Athabasca Basin region of northern Saskatchewan.

TSX- and NYSE MKT-listed Denison said on Wednesday that drill hole WR-689D3 encountered the difficult-to-deal-with style of mineralisation 250 m along strike to the northeast and 200 m up-dip of the Gryphon deposit.

Denison advised that preliminary radiometric equivalent probe results for uranium oxide (eU₃O₈) from the drill hole identified an interval of 5% eU₃O₈ over 4.7 m, including 8.5% eU₃O₈ over 2.7 m, from mineralisation occurring immediately above the sub-Athabasca unconformity that comprises massive to semi-massive uraninite (pitchblende) associated with hydrothermal hematite and clay alteration.

Another high-grade intercept comprises 1.2% eU₃O₈ over 1.4 m.

"The notable high-grade mineralisation intersected at the unconformity, immediately northeast of the Gryphon deposit, presents our Saskatoon-based exploration team with a new and exciting target for additional exploration – with the potential for further drilling to continue to expand resources at Gryphon.

“Coupled with a steady stream of impressive high-grade intersections within the basement-hosted D series lenses, the prospect of significant growth in our estimate of resources for the Gryphon deposit continues to increase as we work towards completing an updated resource estimate following the completion of the summer drilling programme,” stated president and CEO David Cates in a press release.

These so-called E Zone intercepts are new, as previous uranium in this area was hosted in basement rocks. Like D lenses, E Series U₃O₈ has not been incorporated into resources. The E series of lenses represents a new high-priority target area for resource expansion, Denison stated.

“It signals the potential for further unconformity style mineralisation close to existing basement intercepts. It also supports our belief in a large hydrothermal plumbing system at Gryphon, which may mean increased opportunity to find further uranium in the basement or along strike,” Eight Capital analyst David Talbot said in a note to clients.

He believes the intersections could help to greatly expand the 43-million-pound U₃O₈ resource at Gryphon, which itself is gaining critical mass with continued drilling over the past year.

Unconformity deposits are typically larger and higher grade, Talbot points out. However, its discovery here is ironic as two years of Gryphon drilling was designed for resource growth to defer dealing with more problematic unconformity mineralisation at the Phoenix deposit and its 71-million-pound resource, located 3 km away.

“While deferring more costly Phoenix development, it might add a layer of mining complexity to Gryphon. Dealing with overlying altered sandstone host rocks is much more challenging,” Talbot said.