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Amorphous identification and geology

Describing a solid material that lacks the long-range, repeating atomic order characteristic of crystalline substances. In mineralogy, amorphous materials have no defined crystal structure and therefore lack cleavage, exhibit conchoidal fracture, and produce no X-ray diffraction pattern. Some materials classified as amorphous are actually cryptocrystalline, composed of crystals too small to resolve with standard techniques. Field: mineralogy. Example: Opal SiO₂·nH₂O is a mineraloid with an amorphous structure consisting of packed silica spheres rather than a repeating crystal lattice, which is responsible for its characteristic play of color.. Related terms: Crystalline, Cryptocrystalline, Mineraloid.

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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.

Editorial owner
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 Amorphous mean in geology?
Describing a solid material that lacks the long-range, repeating atomic order characteristic of crystalline substances. In mineralogy, amorphous materials have no defined crystal structure and therefore lack cleavage, exhibit conchoidal fracture, and produce no X-ray diffraction pattern. Some materials classified as amorphous are actually cryptocrystalline, composed of crystals too small to resolve with standard techniques.
What is an example of Amorphous?
Opal SiO₂·nH₂O is a mineraloid with an amorphous structure consisting of packed silica spheres rather than a repeating crystal lattice, which is responsible for its characteristic play of color.
Which earth-science field uses the term Amorphous?
Amorphous is used in mineralogy.
Which terms are related to Amorphous?
Related terms in this reference are Crystalline, Cryptocrystalline, Mineraloid.

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