The region northwestern of the Lake Superior is well known for its quartz occurrences - usually amethyst - which occur here in vein-like structures. The Thunderbay Agate mine offered the possibility to collectors and tourists of digging against fee for agates. Here the weight of the chosen specimen was paid. At present the mine is closed. The agates occuring here are vein-agates. The colors are yellowish, red, white and brownish. The vein-agates are patterned by tubes and eye structures.