Black Beach Pebble (Basalt/Greywacke Pebble)
Aphanitic Mafic Igneous Rock / Basalt
igneous
Category
Igneous Or Sedimentary (Water Worn)
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Dark gray-green pebble, likely basalt
Fine-grained basalt (tentative; image alone cannot confirm composition)
igneous
Sandstone (Quartzose Sandstone)
Arenite (SiO2 based)
sedimentary
River Rock
Polished Siliceous Rock / Quartzite Pebble
sedimentary
Dark rounded pebble, likely basalt
Basalt; fine-grained mafic rock composed mainly of plagioclase and pyroxene, commonly with olivine
igneous
Quartz (likely tumbled or naturally water-worn)
Quartz (SiO₂ - Silicon Dioxide)
Mineral
Gneiss (Metamorphosed Pebble)
Gneiss with Quartz/Feldspar banding
metamorphic
Milky Quartz
Silicon Dioxide (SiO2)
mineral
Jasper
Microcrystalline quartz (SiO2) with impurities
sedimentary
Fossilized Gastropod Shell
Gastropoda (Fossilized internal mold or shell body)
fossil
Waterworn Pebble / Quartzite
Metamorphic/Sedimentary rock fragment
sedimentary
Grey River Pebble (Greywacke / Basalt)
Stream-rounded silicate rock pebble
sedimentary
Rounded gray river pebble
Likely quartz-rich metamorphic or igneous pebble; exact identification requires testing
sedimentary
Basalt Pebble
Extrusive Igneous Rock
igneous
Chert with Quartz Vein
Silicon dioxide (SiO2)
sedimentary
Polished banded gneiss or schist pebble
Banded quartz–feldspar–mica gneiss (tentative)
metamorphic
Jasper
SiO2
sedimentary
Quartz Pebble (on Granite)
Silicon Dioxide (SiO2)
mineral
Milky or Iron-Stained Quartz
Quartz (Silicon Dioxide, SiO2)
mineral
Gneiss (Metamorphic Cobble)
Gneiss (High-grade Regional Metamorphic Rock)
metamorphic
Quartz Pebble
Silicon Dioxide (SiO2)
Mineral / Sedimentary
Porous vesicular volcanic rock (likely scoria)
Scoria; chiefly iron-rich volcanic glass with plagioclase, pyroxene, and/or olivine
igneous
Rounded dark pebble, likely basaltic andesite
Fine-grained mafic volcanic rock; probable basalt or andesite, identification uncertain from image alone
igneous
Hag Stone
Perforated Sedimentary Rock (Typically Limestone or Sandstone)
sedimentary
Flint / Chert (Beach-worn Pebble)
Microcrystalline quartz (SiO2)
sedimentary
Jasper Pebble
Silicon dioxide (SiO2) with impurities
sedimentary
Chert (Jasper/Chalcedony)
Microcrystalline Quartz (SiO2)
sedimentary
River Cobble (Basaltic/Andesitic)
Mafic Igneous Porphyritic Rock
igneous
Yellow Quartz / Citrine Pebble
Silicon Dioxide (SiO2)
mineral
River Rock
Siliciclastic rock (water-worn pebble)
sedimentary
Clear quartz crystal (likely tumbled or polished)
Quartz, silicon dioxide (SiO₂)
mineral
Milky Quartz Pebble
Quartz (Silicon Dioxide, SiO2)
mineral
Jasper Pebble
Microcrystalline Quartz (SiO2)
sedimentary
Granite Cobble
Granite
igneous
Brown Chalcedony (Agate/Jasper)
Cryptocrystalline Quartz (SiO2)
mineral
Quartz (Iron-Stained Quartz Pebble)
Silicon Dioxide (SiO2)
mineral
Milky Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Gneiss (specifically a water-worn pebble)
Gneiss
metamorphic
Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Jasper / Chert (River Rock)
Microcrystalline Quartz (SiO2)
sedimentary
Wishing Stone (Basalt or Mudstone with Quartz/Calcite Veins)
Hydrothermally veined Basalt (SiO2/CaCO3 intrusions)
igneous or sedimentary
Banded Agate Pebble
Chalcedony (SiO2)
sedimentary