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Icelandite identification and geology

Icelandite rock reference specimen

Iron-rich intermediate volcanic rock transitional between tholeiitic basalt and rhyolite. Characteristic of Iceland. Texture: Aphanitic to porphyritic. Rock type: Igneous Extrusive. Grain size: Fine. Minerals present: Plagioclase, Augite, Pigeonite, Fe-Ti oxides. Formation: Erupts from tholeiitic volcanic systems where fractional crystallization produces iron-enriched intermediate magmas. Common geological settings: Iceland, Galápagos; found in tholeiitic volcanic provinces. Common look-alikes and related entries: Andesite, Basalt, Dacite.

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
2026-03-30T14:39:33.361349+00:00
Review status
Published; not independently peer-reviewed
  • Rocks — U.S. National Park Service. Authoritative overview of rock groups, the rock cycle, and geologic processes.
  • Can you identify my rock or mineral? — U.S. Geological Survey. Identification limitations and routes to in-person professional verification.

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Common questions

What is Icelandite?
Iron-rich intermediate volcanic rock transitional between tholeiitic basalt and rhyolite. Characteristic of Iceland.
How can you identify Icelandite?
Compare several properties rather than relying on colour alone. This entry records rock type: Igneous Extrusive; texture: Aphanitic to porphyritic; grain size: Fine; common minerals: Plagioclase, Augite, Pigeonite, Fe-Ti oxides. Confirm an important identification with additional field tests or qualified laboratory work.
How does Icelandite form?
Erupts from tholeiitic volcanic systems where fractional crystallization produces iron-enriched intermediate magmas.
Where is Icelandite commonly found?
Iceland, Galápagos; found in tholeiitic volcanic provinces.
What is Icelandite commonly confused with?
Icelandite may be confused with Andesite, Basalt, Dacite. Compare multiple diagnostic properties because colour and surface appearance can overlap.

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