metamorphic
Red Quartzite / Ferruginous Sandstone
Quartzite (SiO2 with iron oxide impurities)
Hardness: 7 (Mohs scale), Color: reddish-brown to purple due to hematite, Luster: dull to vitreous, Crystal structure: microcrystalline/granular, Specific Gravity: 2.6-2.7
Identified More metamorphic →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 (Mohs scale), Color: reddish-brown to purple due to hematite, Luster: dull to vitreous, Crystal structure: microcrystalline/granular, Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone. High heat and pressure Recrystallize quartz grains into a dense, interlocking matrix. Often found in riverbeds after eroding from mountain ranges.
Uses & applications
Used as crushed stone for road construction, railway ballast, and occasionally as decorative stone or landscaping rock due to its durability and color.
Geological facts
Quartzite is so tough that it often breaks through the constituent sand grains rather than around them. It is one of the most weather-resistant rocks on the Earth's surface.
Field identification & locations
Identify in the field by its hardness (it will scratch glass) and its granular, sugary texture on fresh breaks. This rounded specimen indicates significant transport by water in a high-energy environment like a river.
More like this
