sedimentary

Hag Stone

Perforated Flint or Chert (SiO2)

Hardness: 6.5-7. Color: Brown, tan, or gray with naturally occurring pits/holes. Luster: Dull to waxy. Structure: Cryptocrystalline. Cleavage: None (conchoidal fracture).

Hardness: 6
Color: Brown, tan, or gray with naturally occurring pits/holes
Luster: Dull to waxy

Identified July 18, 2026More sedimentary →

Explore Hag Stone in the encyclopedia →

Identify your own rocks.

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

App Store Google Play

Physical properties

Hardness: 6.5-7. Color: Brown, tan, or gray with naturally occurring pits/holes. Luster: Dull to waxy. Structure: Cryptocrystalline. Cleavage: None (conchoidal fracture).

Formation & geological history

Formed as nodules in limestone or chalk through chemical precipitation. The holes are typically created by mechanical erosion from waves or biological boring by organisms like piddock clams over thousands of years.

Uses & applications

Primarily used as amulets, lucky charms, or decorative collection pieces. Historically used as 'witch stones' to ward off bad luck or the 'evil eye'.

Geological facts

Also known as Odin stones, fairy stones, or holy stones. Folklore suggests that looking through the hole allows one to see into the fairy realm or reveal invisible spirits.

Field identification & locations

Identified by naturally occurring, through-and-through holes. Commonly found on beaches, specifically those with flint deposits like the coasts of the UK, Denmark, and the US Great Lakes.