Rock Identifier
River Pebbles (Stream-rounded rocks) (Fluvial Detritus (varied mineralogy)) — Mixed (predominantly sedimentary and igneous)
Mixed (predominantly sedimentary and igneous)

River Pebbles (Stream-rounded rocks)

Fluvial Detritus (varied mineralogy)

Hardness: 5-7 (Mohs scale), Color: shades of grey, tan, and muted pink, Luster: dull to earthy (waxy if wet), Structure: clastic or crystalline depending on specific pebble, Shapes: sub-rounded to rounded with smooth surfaces.

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Physical properties

Hardness: 5-7 (Mohs scale), Color: shades of grey, tan, and muted pink, Luster: dull to earthy (waxy if wet), Structure: clastic or crystalline depending on specific pebble, Shapes: sub-rounded to rounded with smooth surfaces.

Formation & geological history

Formed through mechanical weathering and fluvial erosion. These are small fragments of larger rock formations (like granite, sandstone, or limestone) that have been transported by moving water, smoothing the edges over thousands of years.

Uses & applications

Commonly used in landscaping, decorative stone, construction aggregate, and gravel paths. High-quality smooth stones are also used in spa therapy (hot stones).

Geological facts

The roundness of these stones is a direct indicator of the energy of the water that transported them and the distance they traveled; the smoother the stone, the longer the journey.

Field identification & locations

Identify in the field by their smooth, rounded edges and lack of sharp fractures, usually found in riverbeds, glacial deposits, or beaches. Collectors value them for rock tumbling or decorative garden fillers.

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Other mixed (predominantly sedimentary and igneous) specimens

River Rock (Glacial Cobbles) (Fluvial Alluvium (Mixed lithology including Quartzite, Basalt, and Granite)) — Mixed (predominantly sedimentary and igneous)

River Rock (Glacial Cobbles)

Fluvial Alluvium (Mixed lithology including Quartzite, Basalt, and Granite)

Mixed (predominantly sedimentary and igneous)
Tiffany Stone (Fluorite-bearing Opalized Breccia) — Rock/Mineralized Nodule

Tiffany Stone

Fluorite-bearing Opalized Breccia

Rock/Mineralized Nodule
Engineered Quartz Stone (Agglomerated Quartz (SiO2 + Polymer Resin)) — mineral-based composite

Engineered Quartz Stone

Agglomerated Quartz (SiO2 + Polymer Resin)

mineral-based composite
Glacial Cobbles (predominantly Granite and Gneiss) (Mixed lithologies (Quartz, Feldspar, Mica assemblage)) — igneous and metamorphic

Glacial Cobbles (predominantly Granite and Gneiss)

Mixed lithologies (Quartz, Feldspar, Mica assemblage)

igneous and metamorphic
Granite or Granitic Gneiss (Granitoid / Gneiss) — Igneous / Metamorphic

Granite or Granitic Gneiss

Granitoid / Gneiss

Igneous / Metamorphic
Amethyst (Chevron or Banded Amethyst) (Silicon Dioxide (SiO2) with Fe3+ impurities) — mineral

Amethyst (Chevron or Banded Amethyst)

Silicon Dioxide (SiO2) with Fe3+ impurities

mineral