The Big Thing showing, on the Tut 1 claim, is located 40 kilometres south of Carcross, Yukon Territory at the southeast end of Tutshi Lake, about 70 kilometres west-northwest of Atlin.

The Big Thing occurrence area is mainly underlain by Devonian to Middle Triassic Boundary Ranges Metamorphic Suite greenschist and greenstone that have been intruded by Late Cretaceous granite, and Triassic to Jurassic granitoid intrusions along the Llewellyn fault. These granitoid intrusions occur a few hundred metres southeast of the Gossan (104M 091). Upper Triassic Stuhini Group volcaniclastics and limestone, and Lower Jurassic Laberge Group sediments, occur to the immediate west.

A zone of intense silicification and brecciation contains up to 30 per cent galena, sphalerite, chalcopyrite and arsenopyrite. The mineralization occurs as pods and veins of massive sulphides in brecciated Stuhini Group tuff. A sample from this zone, over 87 centimetres, assayed 6.5 grams per tonne gold and 51.42 grams per tonne silver (Assessment Report 15500, sample R78479).

The Jessie showing (104M 027), to the southwest, was originally staked as the Great Northern Group in 1906. Exploration included hand and blast trenching, which was reported in 1929. The Tut claims were staked in 1986 and 1987 by Noranda to cover a large alteration zone and the source areas for gold-bearing float. The claims cover the Jessie and Big Thing showings. A 1987 geophysical program identified an anomaly on the Tut 7 and 8 claims that appears to be on strike with the Moon Lake showing (104M 057) to the southwest. The anomaly was tested by diamond drilling in 1988 but the results were negative.

In 2004, Marksmen Resources conducted an airborne geophysical survey program over 3 claim blocks consisting of a high-resolution helicopter magnetic, electromagnetic, and radiometric survey. The three blocks consisted of the Bennett Lake - Tannis Block (Main Block) to the west of Tutshi Lake; the Golden Eagle Block to the south and east of Tutshi Lake; and the Reconnaissance Lines to the north and south of the Tannis Block. A total of 661 line-kilometres of geophysical data were acquired, covering an area of approximately 139 square kilometres.

Refer to Tannis (104M 074), Skarn zone (104M 085), Bennett (104M 044) and Camp (104M 090) for geological and work history information.