Lake Superior agate; photo © Scenes & Seens (all rights reserved; used by permission).
Official State Gemstone of Minnesota
Minnesota designated Lake Superior agate as the official state gemstone in 1969. All State Gemstones
An unusually beautiful quartz stone banded with rich red and orange colors (derived from iron ore in the soil), Lake Superior agates were dispersed by glaciers in the last Ice Age. Found in northeastern and north central Minnesota, most Lake Superior agates are pea-size but some are as big as bowling balls and weigh over 20 pounds.
Source
