sedimentary

Hag Stone (Holey Rock / Fossiliferous Limestone)

Limestone (CaCO3) with natural erosion / fossil cavities

AI-generated identification · may be incorrect

Hardness: 3 on Mohs scale (calcite matrix). Color: Light grey to brownish-white. Luster: Dull, earthy. Structure: Non-crystalline, fine-grained clastic/biogenic matrix. Features prominent naturally eroded holes through the body.

Hardness: 3 on Mohs scale (calcite matrix)
Color: Light grey to brownish-white
Luster: Dull, earthy

Identified July 24, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed in shallow marine environments from accumulated calcium carbonate sediment and fossil remains. The distinctive holes are created over time by wave action, water erosion, or burrowing organisms like piddock clams.

Uses & applications

Historically used as protective talismans and folk amulets. Popular among collectors, beachcombers, and crafters for jewelry, wind chimes, and decorative items.

Geological facts

Hag stones, also known as adder stones, witch stones, or holey stones, have rich folklore across Northern Europe. Traditionally, looking through the hole was believed to allow one to see fairies, spirits, or see through illusions and witches' magic.

Field identification & locations

Identified by natural, smooth-edged holes passing entirely or partially through rounded beach pebbles or river rocks. Commonly found along marine beaches, rocky coasts, and riverbeds in limestone-rich regions.