metamorphic
Quartzite
Metamorphic Quartzite (SiO2)
Hardness of 7 on the Mohs scale, color ranges from white and gray to pink, yellow, or orange depending on impurities, vitreous to greasy luster, massive crystal structure with interlocking quartz grains, no true cleavage, specific gravity of 2.65 to 2.75.
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Physical properties
Hardness of 7 on the Mohs scale, color ranges from white and gray to pink, yellow, or orange depending on impurities, vitreous to greasy luster, massive crystal structure with interlocking quartz grains, no true cleavage, specific gravity of 2.65 to 2.75.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and tectonic pressure, typically over hundreds of millions of years in mountain-building zones.
Uses & applications
Used in construction, as crushed stone for roadbeds, in landscaping, countertops, and for manufacturing silica brick and ferrosilicon.
Geological facts
Because quartz is extremely resistant to weathering, quartzite ridges often stand out as high mountain crests and resistant hills in eroded landscapes.
Field identification & locations
Can be identified in the field by its hardness (scratches glass easily), inability to be scratched by a knife, and the way it fractures across grains rather than around them like sandstone.
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