sedimentary

Hag Stone

Perforated Sedimentary Rock (typically Chert or Limestone)

AI-generated identification · may be incorrect

Hardness: 6.5-7 (if chert/flint); Color: tan, brown, or gray; Luster: earthy to dull; Structure: microcrystalline; Features a naturally occurring hole caused by erosion.

Hardness: 6
Color: tan, brown, or gray
Luster: earthy to dull

Identified July 16, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 (if chert/flint); Color: tan, brown, or gray; Luster: earthy to dull; Structure: microcrystalline; Features a naturally occurring hole caused by erosion.

Formation & geological history

Formed through millions of years of water erosion, often in marine or river environments where currents or boring organisms (like piddock clams) create holes in the rock. Many are Palaeogene to Neogene in age.

Uses & applications

Primarily used as amulets, good luck charms, or metaphysical protection. Sometimes used in jewelry or as garden ornaments.

Geological facts

Also known as Odin stones or fairy stones, folklore suggests they protect against nightmares, witchcraft, and the 'evil eye' because 'only good can pass through the hole.'

Field identification & locations

Identify by looking for a hole that has been clearly worn smooth by water or biological activity rather than drilled by a machine. Commonly found on beaches along the UK coast and the Great Lakes.