metamorphic
Quartzite with inclusions or weathered surface
Quartzite
Hardness: 7 (Mohs scale), Color: Light tan or greyish with a darker bluish/grey patch, Luster: Vitreous to dull (depending on weathering), Crystal structure: Granular, interlocking quartz grains, Cleavage: None (conchoidal fracture). It appears smooth, likely river-tumbled.
Identified More metamorphic →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 (Mohs scale), Color: Light tan or greyish with a darker bluish/grey patch, Luster: Vitreous to dull (depending on weathering), Crystal structure: Granular, interlocking quartz grains, Cleavage: None (conchoidal fracture). It appears smooth, likely river-tumbled.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under high heat and pressure, often at tectonic plate boundaries. The smooth, rounded shape indicates it has been weathered and transported by water, such as in a riverbed or coastal environment.
Uses & applications
Used in construction, as railway ballast, decorative landscaping stone, and occasionally for making tools in ancient times due to its conchoidal fracture. Not typically used in fine jewelry.
Geological facts
Quartzite is extremely durable and resistant to chemical weathering. When subjected to pressure, the original quartz grains and the cement holding them together recrystallize into an interlocking mosaic.
Field identification & locations
Identify by its hardness (will scratch glass), sugary or granular texture on fresh breaks, and lack of fizzing with weak acid (unlike marble). Commonly found in areas of past tectonic activity or as rounded cobbles in river deposits.
More like this
