The Three Valley Gap occurrence is located along the Victor Lake main logging road, which joins the Trans-Canada Highway from the south, approximately 3 kilometres east of Three Valley Gap. Outcrop is limited to road-cuts, at elevations between 900 and 1500 metres. The road is in good shape and passable by conventional vehicles.

The area is underlain by paragneiss metamorphic rocks tentatively assigned to the Precambrian- Paleozoic(?) Monashee Complex and undivided metamorphic rocks of the Proterozoic-Paleozoic Shuswap Assemblage.

Locally, carbonatites and syenites occur as thin, discontinuous, bedding-parallel lenses in pelitic metasedimentary rocks. Both the intrusions and the host rocks have been metamorphosed to upper amphibolite facies (sillimanite zone) and the pelites have been extensively migmatized. Carbonatite lenses are generally 20 to 60 centimetres in width and have 10 to 30- centimetre thick envelopes of mafic fenites developed between them and adjacent rocks. Everywhere observed, the fenites are in direct contact with, and gradational to, syenites. Commonly the carbonatite occurs as lenses within the fenite.

The carbonatites are primarily composed of calcite, biotite, apatite, perthite, hornblende, augite and traces of sphene. Fenites generally contain abundant augite, hornblende, calcite, scapolite and plagioclase. The leucosyenites generally contain potassium feldspar, plagioclase, augite and sphene. The origin of the leucosyenites is unclear; unambiguous field relationships are not exposed. These syenites may actually be syenitic fenites, rather than intrusive phases.

In 2010, a rock sample (KP 03-08) of a quartz-feldspar-biotite pegmatite with in a biotite gneiss assayed 0.024 per cent lanthanum, 0.016 per cent neodymium and 0.044 per cent caesium (Assessment Report 32017). In 2015, rock sampling yielded up to 0.045 per cent caesium, 0.025 per cent lanthanum, 0.024 per cent niobium and 0.017 per cent rubidium (Assessment Report 35910).

In 1969, Senate Management completed a program of prospecting, geological mapping, silt sampling and a magnetometer survey on the area immediately east as the Nin claims.

In 2010, Aspiration Mining completed a program or rock and silt sampling on the area as the REE claims. In 2015, Bormal Resources completed a program of rock, silt and soil sampling. These programs were centered on exploration for rare earth elements.