Not A Natural Rock (Man Made Composite)

Sandstone

Arenite

Granite

Granite (Phaneritic Acidic Igneous Rock)

Pea Gravel / River Gravel

Unconsolidated Clastic Sedimentary Aggregate

Diamond Plate (Steel)

Alloyed Carbon Steel or Aluminum with 'Durbar' pattern

Granite

Granite (Felsic Plutonic Rock)

Pale blue-gray quartz-rich pebble (tentative)

Quartz, SiO₂, possibly chalcedony or a weathered metamorphic fragment

Granite

Phaneritic intrusive igneous rock (consisting mainly of Quartz, Alkali Feldspar, and Plagioclase)

Shale (possibly Carbonaceous or Oil Shale)

Laminated Mudstone (primarily clay minerals and quartz)

Chert (Field Stone)

Silicon Dioxide (SiO2)

Yellow Quartz (Chalcedony)

Quartz / Chalcedony (Silicon Dioxide, SiO2)

Boulder Opal

Precious Opal in Ironstone (Amorphous Hydrated Silica, SiO2·nH2O)

Sandstone Pebble

Sedimentary Rock (Quartzose Sandstone)

Quartz

Silicon Dioxide (SiO2)

Biotite-bearing granite or gneiss

Felsic granitoid; chiefly quartz, feldspar, and biotite mica

Sandstone

Arenite

Green Aventurine

Silicon Dioxide (Quartz) with Fuchsite inclusions (SiO2 + K(Al,Cr)2(AlSi3O10)(OH)2)

Chert / Chalcedony Pebble

Cryptocrystalline Quartz (SiO2)

Quartz Pebble (Citrine or Iron-stained Quartz)

Silicon Dioxide (SiO2)

Tumbled dark stone, likely basalt

Basalt; chiefly plagioclase feldspar, pyroxene, and minor olivine or iron oxides

Smoky Quartz Geode

Silicon Dioxide (SiO2)

Quartz Pebble

Silicon Dioxide (SiO2)

Granite

Phaneritic Felsic Igneous Rock

Shale

Fissile mudrock (composed of clay-sized particles and detrital grains)

River Pebble (Granite / Sandstone Cobble)

Stream-rounded Rock Pebble

Pumice

Pumice (a vesicular volcanic glass)

River Rock (Sandstone or Quartzite)

Clastic Sedimentary Rock / Quartzite

Red Granite

Phaneritic Felsic Igneous Rock

Smoky Quartz

Silicon Dioxide (SiO2)

Amethyst

SiO2 (Silicon Dioxide)

Sandstone

Sandstone (principally SiO2)

Sandstone (Ferruginous)

Arenite (composed primarily of SiO2 with Fe2O3 staining)

Amethyst (Agate/Chalcedony variety)

Silicon Dioxide (SiO2) with iron impurities

Shale

Argillaceous Sedimentary Rock

Shale (sub-type: Carbonaceous Shale)

Lutaceous Sedimentary Rock

Granite

Phaneritic plutonic rock (SiO2 primary)

Amethyst

Silicon Dioxide (SiO2)

Pebble (likely a type of sandstone or quartzite pebble)

Clastic Sediment (specifically, a rudite-sized clast). If the pebble is composed of a specific rock type, its scientific name would be that rock type (e.g., 'Quartzite pebble', 'Granite pebble', 'Chert pebble'). Given its appearance, it is likely a metamorphic quartzite pebble or a hard sandstone pebble.

Granite

Phaneritic plutonic rock (primarily Quartz, Alkali Feldspar, and Plagioclase)

Epidotite (Unakite-related)

Epidote-rich rock

Yellow Quartz (Citrine or Iron-stained Quartz)

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Quartzite

Metamorphic Rock (composed primarily of Quartz, SiO2)