sedimentary
Hag Stone
Perforated Sedimentary Rock
Mohs hardness 6-7 (if flint-based), grayish-brown to black, dull luster, microcrystalline structure, naturally occurring hole caused by erosion.
Identified More sedimentary →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Mohs hardness 6-7 (if flint-based), grayish-brown to black, dull luster, microcrystalline structure, naturally occurring hole caused by erosion.
Formation & geological history
Formed primarily through the process of differential erosion where a softer part of the rock (like a fossil or softer mineral inclusion) is washed away by water over centuries, common on beaches and in riverbeds.
Uses & applications
Primarily collected as a curiosity, pocket stone, or for use in jewelry and folk magic. Historically used as amulets for protection.
Geological facts
Also known as adder stones, witch stones, or holy stones, these have been used for thousands of years in European folklore to ward off evil spirits and nightmares.
Field identification & locations
Identify in the field by looking for stones with naturally occuring, smooth-edged holes that penetrate all the way through. Found mostly on coastal beaches with high wave energy.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Shale or Slaty Mudstone
Argillaceous sedimentary rock
sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Chert Breccia
Brecciated Chert (Microcrystalline Silica)
sedimentary
Sandstone (Quartz-rich)
Arenite (SiO2)
sedimentary
Sandstone (with man-made markings)
Arenite (composed primarily of Quartz, SiO2)
sedimentary