Red Sandstone Pebble
Arenite (Iron-oxide stained)
sedimentary
Category
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Serpentine
Antigorite/Lizardite (Mg,Fe)3Si2O5(OH)4
metamorphic
Quartzite
Metamorphic Rock (composed primarily of Quartz, SiO2)
metamorphic
Red Quartzite River Pebble
Quartzite (SiO2 with iron oxide inclusions)
metamorphic
Grey Quartzite Pebble
Quartzite (primarily SiO2)
metamorphic
Blue sodalite-bearing rock, likely sodalite in nepheline syenite
Sodalite (Na₈Al₆Si₆O₂₄Cl₂), possibly in nepheline syenite
mineral
Obsidian
Obsidian (Volcanic Glass; SiO2 content > 70%)
igneous
Chert or flint fragment
Microcrystalline quartz (SiO₂), likely silicified rock
sedimentary
Fossiliferous Limestone
Biogenic Sedimentary Rock (Calcium Carbonate, CaCO3)
sedimentary
Siltstone
Siltstone (fined-grained clastic sedimentary rock)
sedimentary
Granite
Phaneritic plutonic rock (SiO2 typically >69%)
igneous
Granite Cobble
Granite (Phaneritic Quartz-Feldspar-Mica intrusive rock)
igneous
Greenschist
Greenschist facies rock (containing chlorite, actinolite, and epidote)
metamorphic
Quartzite
Metamorphic Quartz (SiO2)
metamorphic
Ferruginous Sandstone
Arenite with Iron-Oxide cement (primarily Fe2O3 • nH2O)
sedimentary
Chert (Jasper/Quartzite variety)
Microcrystalline Silica (SiO2)
sedimentary
Coral Fossil (Petrified Coral)
Scleractinia (Order) - Calcified Fossil Skeleton (CaCO3)
sedimentary
Petrified Wood
Silicified Wood (SiO2)
fossil
Banded Iron Formation (BIF) / Banded Sandstone Nodule
Hematite-rich Sandstone / Ferruginous Chert
sedimentary
Granite
Granite (Felsic Intrusive)
igneous
Granitic gneiss (weathered, rounded cobble)
Foliated granitoid; primarily quartz, feldspar, and mica (composition commonly approximates granite)
metamorphic
Chert (Yellow Jasper/Flint)
Silicon Dioxide (SiO2)
sedimentary
Likely quartz-rich mineral fragment
Quartz (SiO₂), possibly iron-stained or included quartz
mineral
Ferruginous Sandstone
Arenite with Iron-Oxide cement (Fe2O3 · nH2O)
sedimentary
Tumbled basalt (likely)
Basalt; fine-grained mafic volcanic rock composed mainly of plagioclase feldspar and pyroxene, often with minor olivine and iron oxides
igneous
Chert nodules in Limestone
Microcrystalline Quartz (SiO2) in Calcium Carbonate (CaCO3) matrix
sedimentary
Petrified Wood
Silicified Wood (SiO2)
sedimentary
Tumbled agate/chalcedony
Microcrystalline quartz (SiO₂), likely agate or jasper-bearing chalcedony
mineral
Weathered granite or granitic gneiss pebble
Granite; mainly quartz (SiO₂), feldspar, and mica, with possible gneissic alteration
igneous
Chert (varieties include Flint and Jasper)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Conglomerate
Conglomerate (SiO2 matrix with varying clasts)
sedimentary
Olivine in Basalt (Peridot)
Magnesium Iron Silicate (Mg,Fe)2SiO4 (Mineral) / Scoriaceous Basalt (Host Rock)
igneous
Basalt (Water-worn pebble)
Basalt (Aphanitic mafic volcanic rock)
igneous
Chert (Nodule)
Chert (Cryptocrystalline Silica, SiO2)
sedimentary
Weathered sandstone (probable)
Quartz-rich sandstone, largely composed of cemented quartz grains (SiO₂)
sedimentary
Granite
Granitic intrusive igneous rock
igneous
Polished orbicular jasper
Silica-rich microcrystalline quartz/chalcedony (SiO₂), with iron oxides and green alteration minerals
mineral
Conglomerate
Pebble Conglomerate / Clastic Sedimentary Rock
sedimentary
Botryoidal Malachite
Malachite - Cu2CO3(OH)2
mineral
Banded gneiss pebble
Gneiss, commonly quartz–feldspar–mica gneiss
metamorphic
Sandstone with Ironstone Concretion
Arenite with Ferruginous Cement
sedimentary
Green Jasper
Silicon Dioxide (SiO2) with impurities
sedimentary