metamorphic
Quartz-rich metamorphic rock, likely quartzite with mica
Quartzite; predominantly quartz (SiO₂) with probable muscovite/sericite mica and minor iron oxides
AI-generated identification · may be incorrectWhite to gray, slightly greenish and rusty-stained; vitreous to pearly luster with granular, sugary texture. Quartz hardness is Mohs 7, lacks cleavage, and typically forms a dense, tough mass; mica causes flaky sparkle and weak foliation.
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Physical properties
White to gray, slightly greenish and rusty-stained; vitreous to pearly luster with granular, sugary texture. Quartz hardness is Mohs 7, lacks cleavage, and typically forms a dense, tough mass; mica causes flaky sparkle and weak foliation.
Formation & geological history
Formed when quartz-rich sandstone was recrystallized under metamorphic heat and pressure, commonly during mountain building; exact geological age cannot be determined from the photograph.
Uses & applications
Used as crushed stone, aggregate, decorative facing, and durable landscaping rock; attractive pieces are collected but are generally not gem-quality.
Geological facts
Quartzite commonly breaks across quartz grains rather than around them, making it harder than the original sandstone. Green coloration may reflect mica or chlorite, while reddish patches are likely iron-oxide staining.
Field identification & locations
Identify it by its hardness, fused sugary quartz texture, and resistance to scratching by a steel knife; sandstone usually crumbles around grains. Common in metamorphic mountain belts worldwide, including the Appalachians, Rockies, and Precambrian shields.
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