Chert (Iron-stained)
Microcrystalline Quartz (SiO2)
sedimentary
Category
Organic (Non Rock)
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Chert (Green variety)
Silicon Dioxide (SiO2)
sedimentary
Anthracite Coal
Anthracite (Carbon-rich metamorphic sedimentary rock)
sedimentary
Weathered agate or chalcedony nodule
Microcrystalline quartz (SiO₂), likely agate/chalcedony with iron-oxide staining
mineral
Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Fossiliferous Limestone
Sedimentary Calcium Carbonate (CaCO3)
sedimentary
Iron-rich meteorite (probable stony-iron or weathered iron meteorite)
Unclassified meteorite; likely Fe–Ni metal with silicate minerals
meteorite
Red jasper (likely brecciated jasper)
Microcrystalline quartz/chalcedony, SiO₂, colored mainly by iron oxides
mineral
Tumbled greenstone pebble
Likely serpentinite or greenstone; exact identification requires testing
metamorphic
Quartzite Cobble
Quartzite (primarily SiO2)
metamorphic
Quartzite
Quartzite (composed primarily of SiO2)
metamorphic
Quartzite
Quartzite (SiO2)
metamorphic
Polished brecciated jasper
Silicified microcrystalline quartz (SiO₂), commonly called brecciated or ocean jasper
metamorphic
Obsidian
Obsidian (principally SiO2 + MgO, Fe3O4)
igneous
Limestone with Stylolites
Calcareous sedimentary rock (CaCO3)
sedimentary
Conglomerate
Conglomerate (clastic sedimentary rock)
sedimentary
Puddingstone (Conglomerate)
Conglomerate (clastic sedimentary rock)
sedimentary
Chert Pebble Map
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Quartzite Cobble
Quartzite (SiO2)
metamorphic
Chert
Cryptocrystalline Quartz (SiO2)
sedimentary
Chert (Red Jasper variant)
Microcrystalline Quartz (SiO2)
sedimentary
Conglomerate
Conglomerate (SiO2, Al2O3, Fe2O3, CaCo3)
sedimentary
Obsidian
Volcanic glass
igneous
Quartzite
Quartzite (primarily SiO2)
metamorphic
River Siltstone Pebble
Siltstone (primarily composed of silica and clay minerals)
sedimentary
Quartzite
Metamorphic Quartzite (SiO2)
metamorphic
Black Obsidian
Volcanic Glass (SiO2 + impurities)
igneous
Fossil Shark Tooth
Selachii (fossilized dentition)
fossil
Likely basalt (possibly a dark beach pebble)
Basalt; fine-grained mafic volcanic rock composed mainly of plagioclase and pyroxene, commonly with olivine
igneous
Fossiliferous limestone pebble
Bioclastic limestone, commonly calcitic (CaCO₃)
sedimentary
Native gold nuggets
Gold (Au), usually with minor silver and copper
mineral
Diorite (Spotted or Dalmatian Stone pattern)
Diorite
igneous
Chert (Flint)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Quartzite Cobble (Iron-stained)
Quartzite (SiO2)
metamorphic
Obsidian
Volcanic Glass (Amorphous SiO2)
igneous
Chert with Quartz Vein
Silicon dioxide (SiO2)
sedimentary
Conglomerate
Conglomerate (clastic sedimentary rock)
sedimentary
Basalt River Pebble
Basalt (Mafic Volcanic Rock)
igneous
Graphite-bearing schist (probable)
Graphite schist; chiefly quartz, mica, and graphite
metamorphic
Quartzite Pebble (River Rock)
Quartzite (mainly SiO2)
metamorphic