sedimentary

Hag Stone

Natural Perforated Flint or Chert (SiO2)

Hardness: 6.5-7 Mohs. Color: Dull grey, brown, or greenish with orange-iron staining. Luster: Dull/Waxy. Structure: Cryptocrystalline. Feature: A natural bore hole caused by boring organisms or water erosion.

Hardness: 6
Color: Dull grey, brown, or greenish with orange-iron staining
Luster: Dull/Waxy

Identified July 10, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed over millions of years through sedimentary processes. The distinctive hole is typically created by the burrowing of piddock clams or the consistent acidic erosion of water against a softer inclusion in the mineral matrix.

Uses & applications

Traditionally used as protective amulets in folklore; also popular for home decoration, curio collecting, and spiritual practices.

Geological facts

Also known as 'Odin stones', 'fairy stones', or 'witch stones'. In European folklore, looking through the hole was said to reveal the invisible world of fairies or protect against evil spirits.

Field identification & locations

Identified by a naturally occurring hole through the stone. Commonly found on beaches or in riverbeds where water action and marine life (like boring mollusks) are present. They are prized by beachcombers.

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