Tonalite
Rock
Also called Trondhjemite (light-coloured variety)
About it
Salt-and-pepper rock of quartz and white plagioclase with black biotite and hornblende but almost no potassium feldspar, so it lacks the pink of granite. Common in ancient shield crust and in the Coast Mountains of British Columbia.
- Type
- Rock (igneous)
- Group
- Igneous (plutonic)
- Specific gravity
- 2.65–2.9
- Colours
- light to medium grey, white, speckled with black
- Transparency
- opaque
Typical values: real specimens vary. For more, see mindat.org.