metamorphic
Quartzite
Quartzite (chiefly SiO2)
Hardness: 7 (Mohs scale), Color: White to grayish-tan with potential banding, Luster: Vitreous to dull, Crystal structure: Trigonal (microcrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.63-2.65
Identified More metamorphic →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 (Mohs scale), Color: White to grayish-tan with potential banding, Luster: Vitreous to dull, Crystal structure: Trigonal (microcrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.63-2.65
Formation & geological history
Formed through the regional metamorphism of quartz sandstone. Under intense heat and pressure, the individual quartz grains recrystallize and fuse into a solid, interlocking mass of quartz crystals.
Uses & applications
Used primarily in construction for road ballast, floor tiles, and countertop surfaces. Also used as a source for silica in glass manufacturing and as a decorative stone in landscaping.
Geological facts
Quartzite is so strong that when it breaks, the fracture passes through the quartz grains rather than along the boundaries between them, which is a key differentiator from its parent rock, sandstone.
Field identification & locations
Found globally in mountain belts; can be identified by its grainy texture that does not rub off like sand and its ability to scratch glass. It is often resistant to weathering and forms prominent ridges.
More like this
