Tonalite identification and geology

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• Previous: Tillite — Lithified glacial till composed of unsorted sediment deposited directly by glacial ice. Contains fragments of all sizes.
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• Granodiorite
• Diorite
• Trondhjemite

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

2026-03-30T14:37:21.25463+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 Tonalite?

Quartz-bearing intermediate plutonic rock with plagioclase as the dominant feldspar. Part of the TTG suite.

How can you identify Tonalite?

Compare several properties rather than relying on colour alone. This entry records rock type: Igneous Intrusive; texture: Phaneritic; grain size: Coarse; common minerals: Plagioclase, Quartz, Biotite, Hornblende. Confirm an important identification with additional field tests or qualified laboratory work.

How does Tonalite form?

Crystallizes from intermediate magmas in continental arc settings. Important in Archean TTG terranes.

Where is Tonalite commonly found?

Western Alps Tonale Pass , Andes, Archean cratons; found in continental arc batholiths.

What is Tonalite commonly confused with?

Tonalite may be confused with Granodiorite, Diorite, Trondhjemite. Compare multiple diagnostic properties because colour and surface appearance can overlap.