Filed Under Environment

Intersection of BA&P Trail with Main St.

The south side of the rock-cut displays Oxidized ore veins and veins that were not ore-bearing cutting through the Butte granite. Veins, or dikes, are sheet-like narrow igneous bodies (once molten rock) that intrude into the granite along upright fractures. All three rock types were used as building stones in Butte.


Untitled Nearly vertical oxidized ore vein cutting through granite on the south side of the trail.
Untitled The rock outcrop on the south side of the trail is mostly granite but has reddish-brown colored oxidized ore veins cutting through at orientations nearly parallel to the walking trail. Some of the veins can be seen to appear in outcrops on the north side of the trail.
Untitled Nearly vertical wide oxidized ore vein on the south side of the trail.
Untitled The oxidized ore vein rock is noted by the reddish-brown color between grayish granite.
Untitled Closeup of oxidized ore vein rock. Note that the blackish-brown rock on either side of the vein is hard, well-cemented rock. The oxides in the rock are of manganese and iron. This hard rock was extensively used in rubble-rock walls and foundations in Butte.
Untitled This outcrop of fractured granite is gray, showing that the minerals have not been oxidized to reddish-brown colors. Where less fractured, this granite could be quarried for building stone.


Location: Latitude 46.01910 Longitude -112.53678


Larry Smith, “Intersection of BA&P Trail with Main St.,” Story of Butte, accessed April 14, 2024,