igneous
Granitoid
Granitoid (comprising Quartz, Feldspar, and Mica/Amphiboles)
Hardness: 6-7 Mohs; Color: Gray, tan, and white mottled; Luster: Dull to vitreous; Crystal structure: Phaneritic (coarse-grained); Specific gravity: 2.6-2.7
- Hardness
- 6-7 Mohs
- Color
- Gray, tan, and white mottled
- Luster
- Dull to vitreous
Identified More igneous →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6-7 Mohs; Color: Gray, tan, and white mottled; Luster: Dull to vitreous; Crystal structure: Phaneritic (coarse-grained); Specific gravity: 2.6-2.7
Formation & geological history
Formed from the slow cooling of magma deep beneath the Earth's surface (intrusive igneous). These rocks are found in continental crust and occur throughout various geological eras, including the Precambrian.
Uses & applications
Used widely in construction (aggregate, paving), countertops, monument stone, and as common architectural masonry.
Geological facts
Granitoids represent the foundational building blocks of the Earth's continents; they are much less dense than oceanic crust, allowing continents to 'float' higher on the mantle.
Field identification & locations
Identify in the field by its interlocking crystal texture and extreme hardness (cannot be scratched by steel). Commonly found in mountain ranges and eroded riverbeds.
