metamorphic
Yellow Quartzite (River Pebble)
Quartzite (primarily SiO2)
Hardness: 7 (Mohs scale), Color: Yellowish-tan to honey gold, Luster: Vitreous to waxy (especially when water-worn), Crystal Structure: Trigonal (microcrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.63 - 2.65
Identified More metamorphic →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 (Mohs scale), Color: Yellowish-tan to honey gold, Luster: Vitreous to waxy (especially when water-worn), Crystal Structure: Trigonal (microcrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.63 - 2.65
Formation & geological history
Formed through the metamorphism of quartz sandstone under intense heat and pressure, typically in orogenic (mountain-building) belts. This specific specimen shows signs of alluvial weathering, having been smoothed by river or beach water action.
Uses & applications
Crushed quartzite is used in road construction and as railway ballast. High-purity quartzite is used to produce ferrosilicon and silicon metal. Rounded pebbles like this are popular for xeriscaping, aquarium decor, and tumbling.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rock during erosion, leaving behind high ridges or resistant pebbles in riverbeds. It is often confused with marble, but can be distinguished because quartzite will scratch glass and does not fizz in acid.
Field identification & locations
Identify in the field by its extreme hardness and grainy, sugary texture under a lens. It is found globally in ancient mountain ranges and river deposits. Collectors should look for smooth, translucent pieces that lack visible individual sand grains.
More like this
