Igneous Or Sedimentary (Water Worn)

Carnelian

Carnelian (Silicon Dioxide, SiO2)

Green Chalcedony

Silicon Dioxide (SiO2) with trace minerals

Onyx Marble (Banded Calcite)

Calcite (Calcium Carbonate, CaCO3)

Blue Chalcedony

Silicon Dioxide (SiO2)

Milky Quartz Pebble

Silicon Dioxide (SiO2)

Quartz Pebble (Grit)

Silicon Dioxide (SiO2)

Quartz / Iron-Stained Quartz

Silicon Dioxide (SiO2) with iron oxide inclusions/staining

Amazonite

Amazonite (KAlSi3O8 - Microcline)

Milky Quartz

Silicon Dioxide (SiO2)

Pumice

Vesicular volcanic glass (primarily Alumino-silicates)

Aquamarine

Beryl (Be3Al2Si6O18 with Fe2+ impurities)

Granodiorite (River Pebble)

Granodiorite

Pumice

Pumice (a highly vesicular volcanic glass)

Quartz (River Pebble)

Silicon Dioxide (SiO2)

Sandstone

Arenite

Pumice

Pumice (a highly vesicular extrusive igneous rock)

Sandstone

Arenite (Secondary classification based on grain size)

Ferruginous Sandstone (with ripple marks)

Arenite with Iron-Oxide (Fe2O3) cement

Sandstone (Graywacke type)

Clastic Sedimentary Rock (Lithic Sandstone)

Sandstone (with Iron Staining)

Clastic Sedimentary Rock (primarily SiO2 with FeO(OH) impurities)

Granite Cobble

Granite (Felsic Intrusive)

Granite Pebble

Phaneritic Felsic Igneous Rock (Granite)

Pumice

Pumice (a vesicular volcanic glass)

River Pebbles (Stream-rounded rocks)

Fluvial Detritus (varied mineralogy)

Pumice

Pumice (Vesicular volcanic glass)

Magnetite (Iron Ore)

Magnetite (Fe3O4)

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.

Calcite

Calcite (Calcium Carbonate, CaCO3)

Sandstone (Ferruginous)

Arenite (Fe-rich)

Pumice

Pumicite (Amorphous Volcanic Glass)

Granitic Pegmatite with Tourmaline/Chlorite

Pegmatite

Sandstone (Ferruginous)

Arenite with Iron Oxide cement

Scoria (Lava Rock)

Scoria

Pumice

Pumice (Amorphous volcanic glass)

Black Obsidian

Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide) with impurities

Pyrite

Iron Sulfide (FeS2)

Pumice

Vesicular volcanic glass

Black Opal

Amorphous Hydrated Silica (SiO2·nH2O)

Halite (Rock Salt)

Halite (NaCl)

Vesicular Basalt (Scoria)

Vesicular Basalt

Granite Pebble

Granite (Phaneritic intrusive igneous rock)

Sedimentary Sandstone (Sandstone Slab)

Arenite (SiO2 with Fe2O3 staining)