The Foghorn occurrence is located 10 kilometres northeast of Ymir. Workings comprise several open cuts, short adits and inclined shafts on 3 veins, the No. 1, No. 2 and No. 3.

The area is underlain by porphyritic and gneissic granodiorite (Nelson batholith) of the Middle to Late Jurassic Nelson Intrusions which host north-northeast trending pendants. The pendants comprise Lower Jurassic Ymir Group sediments striking 010 to 082 degrees. The sediments have been metamorphosed to quartz-biotite schist and biotite schist. The veins and country rocks are crosscut by lamprophyre dykes.

The granodiorite is host to several northeast trending, faulted quartz veins of variable dip and strike. The veins are in the order of 20 to 30 centimetres wide on average. The veins contain quartz with pyrite and are sheared. Breccia and fault gouge 5 to 10 centimetres wide is common. Quartz near surface is vuggy and small crystals of quartz are noted. Manganite is common in the veins with some limonite. The granitic host rock is kaolinized locally. The No. 1 vein, the most northerly and highest vein, strikes 008 degrees and dips 52 degrees west. The footwall is aplitic granodiorite grading into gneiss and the hanging wall is normal granodiorite. The granodiorite contains small angular veins of honey-combed and, locally, iron stained quartz. These vary from 0.15 to 0.60 metre in width.

The No. 2 vein, the most southerly and lowest vein, is exposed in an open cut 76 metres lower than the No.1 vein. The No. 2 vein strikes 040 degrees and dips 45 to 50 degrees north. The vein in the face shows 0.03 metre of quartz hosting pyrite and limonite with several centimetres of oxidized and kaolinized granitic vein rock.

The No. 3 vein, traversing the area in between No.1 and No.2, is exposed by 3 surface cuts, a shaft and an adit. The vein exposed is 0.5 to 1 metre wide and both walls are in granodiorite. The vein strikes 033 degrees and dips 053 degrees north and is truncated by a lamprophyre dyke. This vein reportedly carries the best gold values. Samples collected from the collar of the shaft and from dump material near the portal assayed up 74.7 grams per tonne gold (Sample FHTDD-3), (Assessment Report 16464).

Records indicate a zone 2.75 metres wide of high grade galena and a 14 metre zone of low grade galena (about 7.5 per cent) within what is referred to as the "long tunnel". It is unclear which vein each of these zones may be associated with.