Rock Identifier
River Pebble (likely Quartzite or Chert) (Silicon Dioxide (SiO2)) — metamorphic or sedimentary
metamorphic or sedimentary

River Pebble (likely Quartzite or Chert)

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: Approx. 7 (Mohs scale), Color: Tan, brown, or buff with mottling, Luster: Dull or sub-waxy (waxy when wet), Crystal structure: Microcrystalline or non-clastic, Cleavage: None/Conchoidal fracture.

Hardness
Approx
Identified More metamorphic or sedimentary →
Explore River Pebble (likely Quartzite or Chert) in the encyclopedia →

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Physical properties

Hardness: Approx. 7 (Mohs scale), Color: Tan, brown, or buff with mottling, Luster: Dull or sub-waxy (waxy when wet), Crystal structure: Microcrystalline or non-clastic, Cleavage: None/Conchoidal fracture.

Formation & geological history

Formed through the erosion and transport of larger rock masses (such as sandstone or metamorphic quartzite) by water. The rounded shape indicates significant travel in a river or stream bed where abrasive forces smoothed the edges.

Uses & applications

Commonly used in landscaping, decorative ground cover, aquarium gravel, and construction aggregate. If high in quartz, it can be used for tumbling by hobbyists.

Geological facts

River pebbles are smoothed by the natural process of 'attrition,' where rocks collide with one another in moving water, effectively sandblasting themselves over years or decades.

Field identification & locations

Identify by its rounded, smooth 'water-worn' texture and lack of sharp edges. These are ubiquitous in riverbeds, glacial deposits, and coastal areas.

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Banded gneiss

Gneiss, commonly quartz–feldspar–mica gneiss

metamorphic
Small quartz-rich mineral fragment (Quartz (SiO₂), possibly milky or chalcedonic quartz) — mineral

Small quartz-rich mineral fragment

Quartz (SiO₂), possibly milky or chalcedonic quartz

mineral
Quartz vein fragment (Quartz, silicon dioxide (SiO₂), likely milky to translucent quartz with iron-oxide or clay inclusions) — mineral

Quartz vein fragment

Quartz, silicon dioxide (SiO₂), likely milky to translucent quartz with iron-oxide or clay inclusions

mineral
Quartz-rich rock, possibly milky quartz or quartzite (Quartz (SiO₂); if quartzite, recrystallized quartz sandstone) — metamorphic

Quartz-rich rock, possibly milky quartz or quartzite

Quartz (SiO₂); if quartzite, recrystallized quartz sandstone

metamorphic
Tumbled quartz pebble, possibly citrine or pale smoky quartz (Quartz (SiO₂), likely microcrystalline/tumbled material) — mineral

Tumbled quartz pebble, possibly citrine or pale smoky quartz

Quartz (SiO₂), likely microcrystalline/tumbled material

mineral
Unidentified greenish-gray rock fragment (Tentatively altered basalt or basaltic volcanic rock; mineral identification requires testing) — igneous

Unidentified greenish-gray rock fragment

Tentatively altered basalt or basaltic volcanic rock; mineral identification requires testing

igneous