metamorphic
Quartzite with Chert inclusions
Metamorphosed Quartz-rich Rock (SiO2)
Hardness: 7 (Mohs scale), Color: tan to creamy white with dark grey/brown patches, Luster: vitreous to waxy, Crystal structure: microcrystalline, Cleavage: none (conchoidal fracture), Specific gravity: 2.6-2.7
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Physical properties
Hardness: 7 (Mohs scale), Color: tan to creamy white with dark grey/brown patches, Luster: vitreous to waxy, Crystal structure: microcrystalline, Cleavage: none (conchoidal fracture), Specific gravity: 2.6-2.7
Formation & geological history
Formed from the metamorphism of quartz sandstone (protolith) under intense heat and pressure, likely during an orogenic event. The darker areas represent chert or original sedimentary impurities captured during recrystallization.
Uses & applications
Primarily used as construction aggregate, crushed stone for road base, or as an ornamental stone in landscaping. High-quality specimens are collected for geological study.
Geological facts
Quartzite is so hard that it can often cut through the sand grains of the original rock rather than around them. It is one of the most durable rocks on the Earth's surface and is highly resistant to chemical weathering.
Field identification & locations
Identify in the field by its inability to be scratched by steel and its grainy but fused texture. Often found in glaciated areas as 'river cobbles' or in metamorphic mountain belts. Collectors look for unique banding and colorful inclusions.
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