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Conchoidal fracture identification and geology

A type of fracture that produces smooth, curved surfaces resembling the interior of a shell, typically with concentric ridges radiating from the point of impact. Conchoidal fracture is characteristic of amorphous or very fine-grained materials with uniform bonding in all directions, most notably volcanic glass obsidian , quartz, flint, chert, and opal. It was exploited by early humans for making sharp-edged stone tools. Field: mineralogy. Example: Obsidian fractures conchoidally to produce extremely sharp edges—sharper than surgical steel scalpels at the molecular level—which is why it was prized for tools and weapons by ancient cultures worldwide.. Related terms: Fracture, Cleavage, Obsidian, Flint.

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Sources, scope & corrections

These authoritative resources support category-level nomenclature, terminology, identification methods, and safety. When a specimen-specific safety warning appears, the public-health source listed here directly supports that precaution. They are not line-by-line citations for every other property on this entry, and natural specimens vary.

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GeoMiner
Last updated
2026-03-30T15:19:41.970235+00:00
Review status
Published; not independently peer-reviewed
  • USGS Thesaurus — U.S. Geological Survey. Controlled earth-science terminology used to describe USGS information resources.
  • Glossary of Geologic Terms — U.S. National Park Service. Geologic definitions prepared by the NPS Geologic Resources Inventory.

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Common questions

What does Conchoidal fracture mean in geology?
A type of fracture that produces smooth, curved surfaces resembling the interior of a shell, typically with concentric ridges radiating from the point of impact. Conchoidal fracture is characteristic of amorphous or very fine-grained materials with uniform bonding in all directions, most notably volcanic glass obsidian , quartz, flint, chert, and opal. It was exploited by early humans for making sharp-edged stone tools.
What is an example of Conchoidal fracture?
Obsidian fractures conchoidally to produce extremely sharp edges—sharper than surgical steel scalpels at the molecular level—which is why it was prized for tools and weapons by ancient cultures worldwide.
Which earth-science field uses the term Conchoidal fracture?
Conchoidal fracture is used in mineralogy.
Which terms are related to Conchoidal fracture?
Related terms in this reference are Fracture, Cleavage, Obsidian, Flint.

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