Gems of Geoscience
Chad Sorba, P. Geo.
In this regular section of The Professional Edge, we learn about geoscientists and their profession through their favourite rocks. In this issue, we talk with Chad Sorba, P.Geo., a technical services manager at Denison Mines Corp.
Phoenix- Arising from the Ashes
he Phoenix deposit is the world’s highest-grade, undeveloped uranium deposit located on Denison Mines Wheeler River Project in the eastern portion of the Athabasca Basin in northern Saskatchewan. The Wheeler River property had been extensively explored since the late 1970s, but it was not until 2008 when the Phoenix deposit was discovered.
Denison’s former vice-president of exploration dubbed the deposit “Phoenix” because of extensive previous exploration that resulted in this deposit seemingly rising from the ashes.
The Phoenix deposit straddles the sub-Athabasca unconformity approximately 400 metres below surface and comprises three zones which cover a strike length of 1.1 kilometres.
The deposit consists of an exceptionally high‐grade core surrounded by a lower grade shell. Mineralization within the Phoenix deposit is dominated by massive to semi-massive uraninite (also known as pitchblende) associated with an alteration assemblage comprising hematite, dravitic tourmaline, illite and chlorite. Secondary uranium minerals (including uranophane) and sulphides are trace in quantity.
The deposit had a relatively complex history as it formed by an extensive hydrothermal system. This created a vast array of alteration surrounding the deposit within the Athabasca Basin sandstones above. The alteration system, structural setting and mineralization has always intrigued me to learn more about uraninite and the deposit itself. Notably, the density of the mineralization, which is not uncommon to be up to three times that of the surrounding sandstones. The shear weight of holding up a piece of mineralized core from the Phoenix deposit is something that will never cease to impress me. It has been a great privilege to work on the Phoenix deposit for more than a decade. The high-grade nature of the deposit has always been a drawing point for me to learn more about the deposit and how it might be economically extracted considering its world-class grades.