igneous/metamorphic
Granite / Gneiss Complex
Felsic Plutonic Rock (Granite) or High-grade Metamorphic Rock (Gneiss)
Hardness 6-7 (Mohs scale), colors ranging from light gray to pinkish-gray with darker speckles. Luster is earthy to vitreous depending on mica content. Features a crystalline or foliated texture with a specific gravity of 2.65-2.75.
Identified More igneous/metamorphic →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness 6-7 (Mohs scale), colors ranging from light gray to pinkish-gray with darker speckles. Luster is earthy to vitreous depending on mica content. Features a crystalline or foliated texture with a specific gravity of 2.65-2.75.
Formation & geological history
Formed through the slow cooling of magma deep beneath the Earth's surface (igneous) or through the high-pressure/temperature transformation of pre-existing rocks (metamorphic). These formations can range from Proterozoic to more recent geological eras.
Uses & applications
Extensively used in construction for aggregate, paving stones, and dimension stone (countertops/monuments). Also used as a durable material for outdoor landscaping and embankments.
Geological facts
Granite makes up a significant portion of the Earth's continental crust. When subjected to intense heat and pressure, it can transform into Gneiss, displaying characteristic banding layers known as 'gneissic foliation'.
Field identification & locations
Identify in the field by its interlocking crystal grains of quartz, feldspar, and darker minerals like biotite. It is common in mountain ranges and shield regions. To identify, look for a 'salt and pepper' appearance and resistance to scratching by steel.
More like this
Other igneous/metamorphic specimens
Blue Apatite
Apatite (Group), Ca5(PO4)3(F,Cl,OH)
mineral
Nephrite Jade
Nephrite
Mineral/Rock
Sapphire
Corundum (Al2O3)
mineral
Blue Apatite
Apatite-(CaF), Ca5(PO4)3F (Calcium Fluorophosphate)
mineral
Magnetite
Magnetite (Fe3O4)
mineral
Zoisite with Ruby (Anyolite)
Zoisite – Ca2Al3(SiO4)3(OH) with inclusions of Ruby (Al2O3:Cr)
metamorphic