The Grandoro past-producing gold-silver mine is located about 2.3 kilometres north of Orofino Mountain, 12 kilometres north-east of Keremeos, in the Osoyoos Mining Division.

The deposit and the surrounding geology are described on the British Columbia Minfile page, current to August 2007; selected parts of the description are quoted, as follows:

“The Grandoro property is located within the Intermontane Belt near its eastern boundary with the Omineca Belt. The property is underlain by complexly deformed metamorphic rocks of the Carboniferous to Permian Kobau Group, and west and northwest trending sequences of quartzite, chert and greenstone belonging to the Carboniferous to Triassic Shoemaker and Old Tom formations. These are intruded by gabbroic to granitic rocks of the Middle Jurassic Nelson plutonic complex and Similkameen batholith, Jurassic Oliver plutonic complex and Jurassic to Cretaceous Fairview intrusion. Eocene vesicular basalts of the Marron Formation, Penticton Group are block-faulted against older rocks on the north and west sides of the property.

On the northwestern slopes of Orofino Mountain, the oldest rocks are quartzite of the Kobau Group. Light grey, massive to thinly bedded quartzites of the Shoemaker Formation form two relatively narrow bands which strike west and northwest, and dip mainly to the southwest at 70 to 80 degrees. These rocks are adjacent to altered dioritic rocks, varying from massive coarse-grained hornblende gabbros and biotite diorite, to fine-grained biotite schist. Near the quartzite-diorite contact, mineralized quartz veins strike north to northeast and dip moderately to steeply to the southeast or steeply to the west.

The best mineralized veins in the Orofino Mountain gold camp appear to strike north to northeast and dip 45 degrees southeast to near vertical. Trenching and drilling in 1987 have revealed a complex fault pattern which displaces veins left laterally by steep northeast faults or shallow faults. The intersection of these faults with veins appears to structurally control gold values.”

Giles Peatfield comments:

The question of production from the Grandoro mine is complex and not fully clear. Minfile gives the following summary:
“Intermittent total recorded production for the Grandoro occurrence between 1899 and 1941 was 12,048 tonnes mined and 10,228 tonnes milled. From this, 37,853 grams of silver, 123,698 grams of gold, 79 kilograms of lead and 5 kilograms of zinc were recovered.”

At least some of the milled ore was derived from other sources, so the totals given are perhaps inflated. In summary, Orofino Mountain was a modest gold-silver producer.

Comments on the minerals reported:

The minerals listed were reported by Cavey and Raven (1988), from surface exposures, trenches and underground mapping, with the exception of galena and native gold that were identified by Freeland (1934). These are all field identifications.

Of special interest is the presence of rhodonite. Cavey and Raven (1988) noted rhodonite in Trench TR-88-18, with pyrite in what they described as a ‘glassy qtz section’. Leaming (1966) wrote that “Rhodonite is reported from Orofino Mountain (Wm. Moldowin - personal Communication) . . . . It is not known whether it is in the Shoemaker Formation but it appears likely that it is.” Leaming (1973) noted that “Rhodonite is reported from the north slope of Orofino Mountain but the exact locality is not known. Figure 23 [sic - 24] shows the approximate location

Comments on the rock types reported:

The names of the rocks listed are from the report by Cavey and Raven (1988), with the exception of schist, which was named by Freeland (1934). These are field identifications.

Research by Giles Peatfield, Courtenay, British Columbia.
Posting prepared 13 April, 2026.

Other Databases

Link to British Columbia Minfile:	082ESW010

Other Regions, Features and Areas containing this locality

References