mineral

Lake Superior Agate

Cryptocrystalline Quartz (SiO2)

Hardness: 7 Mohs; Color: Red, orange, white, and translucent; Luster: Vitreous to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: None; Specific gravity: 2.60-2.65

Hardness: 7 Mohs
Color: Red, orange, white, and translucent
Luster: Vitreous to waxy

Identified May 19, 2026More mineral →

Explore Lake Superior Agate in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness: 7 Mohs; Color: Red, orange, white, and translucent; Luster: Vitreous to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: None; Specific gravity: 2.60-2.65

Formation & geological history

Formed in gas vesicles (bubbles) of basaltic lava flows approximately 1.1 billion years ago during the Midcontinent Rift system. Iron leached from the basalt provides the signature red and orange coloration.

Uses & applications

Highly prized by collectors, used in lapidary work for jewelry, tumbling, and decorative display pieces.

Geological facts

The Lake Superior Agate was designated as the official state rock of Minnesota in 1969. It is famous for its concentration of iron-rich red bands.

Field identification & locations

Identified by concentric banding, waxy texture, and translucency. Commonly found on beaches of Lake Superior and in glacial till throughout the Upper Midwest, particularly Minnesota and Wisconsin. Collectors look for 'windows' into the banding.