The Llewellyn Inlet occurrence is located at the foot of Llewellyn Glacier at the south end of Atlin Lake, about 45 kilometres southwest of the community of Atlin.

The showing area lies within a narrow wedge of Upper Triassic Stuhini Group andesites and basalts bordered to the west by intrusive rocks of the Late Triassic Stikine Plutonic Suite and to the east by Lower Jurassic sedimentary and volcanic rocks of the Laberge Group. This small segment of Upper Triassic volcanics is juxtaposed against the Laberge Group by the King Salmon fault to the east. In the west, rocks of the Stikine Plutonic Suite are also in fault contact with the Stuhini Group.

The occurrence consists of two copper showings. The main showing comprises a narrow quartz stringer filled with massive chalcocite along which an adit was driven from the east shore of the inlet. There is a second showing of a copper stained (malachite) pyrite zone located in a creek flowing west into the north end of the inlet.

A hand sample from the quartz stringer zone was sampled in 1904 and assayed 6.1 per cent copper, 3133 grams per tonne silver, and 1.02 grams per tonne gold (Minister of Mines Annual Report 1904).

In 1904, the Union claim group covered the Llewellyn Inlet occurrence.