metamorphic
Quartz-rich metamorphic rock, likely quartzite
Quartzite; predominantly crystalline SiO₂, with minor gray mica/graphite or accessory minerals
AI-generated identification · may be incorrectWhite to gray, granular and nonmetallic with vitreous to sugary luster; quartz hardness ~7 Mohs, no cleavage, irregular fracture, and typically high toughness. The dark wispy bands and yellowish staining suggest minor mica/graphitic inclusions and iron oxides, though a firm identification requires a fresh surface and t…
Identified More metamorphic →
Explore Quartz-rich metamorphic rock, likely quartzite in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
White to gray, granular and nonmetallic with vitreous to sugary luster; quartz hardness ~7 Mohs, no cleavage, irregular fracture, and typically high toughness. The dark wispy bands and yellowish staining suggest minor mica/graphitic inclusions and iron oxides, though a firm identification requires a fresh surface and testing.
Formation & geological history
Forms when quartz-rich sandstone is recrystallized under heat and pressure during regional metamorphism; ages vary widely, commonly Precambrian to Paleozoic. It occurs in metamorphic mountain belts and exposed resistant ridges.
Uses & applications
Used as crushed stone, aggregate, building stone, countertops, and decorative specimens; particularly attractive pieces may be polished. Its durability makes it useful where abrasion resistance is important.
Geological facts
Quartzite commonly resembles marble but does not fizz with dilute hydrochloric acid and is generally harder. If individual quartz grains remain visibly sandy and the rock scratches glass, quartzite is likely.
Field identification & locations
Common worldwide, including the United States, Brazil, India, Scandinavia, and the Alps. Test with a steel knife and glass, inspect for interlocking quartz grains, and use acid only to distinguish carbonate rocks.
More like this
