Limestone
Calcium Carbonate (CaCO3)
sedimentary
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Granite
Intrusive Igneous Rock
igneous
Basalt
Extrusive Igneous Rock
igneous
Quartz Rock
Silicon Dioxide (SiO2)
mineral
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Basalt Pebble
Extrusive igneous rock
igneous
Sandstone Concretion
Sedimentary Concretion (Quartz sandstone with iron oxide cement)
sedimentary
Quartz
Silicon Dioxide (SiO2)
mineral
Turtle Stone / Septarian Nodule (Water-worn)
Septarian Concretion
sedimentary
Agate Nodule
Silicon Dioxide (Chalcedony / Quartz), SiO2
sedimentary
Agate
Silicon dioxide (Chalcedony), SiO2
sedimentary
Quartzite Pebble
Metamorphic Quartzite (SiO2)
metamorphic
Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Waterworn Pebble / Quartzite
Metamorphic/Sedimentary rock fragment
sedimentary
Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Flint (or Chert with Chalk/Limestone)
Microcrystalline quartz (SiO2) nodule
sedimentary
Quartzite Pebble
Quartzite
metamorphic
Flint / Chert (Fossiliferous)
Silicon dioxide (SiO2) with microcrystalline quartz
sedimentary
Flint / Chert with Fossils
Cryptocrystalline quartz (SiO2) with embedded fossil impressions
sedimentary
Flint (or Chert)
Microcrystalline Quartz (SiO2)
sedimentary
Jasper
Microcrystalline Quartz (SiO2)
sedimentary
Flint / Chert with Cortex
Microcrystalline Quartz (SiO2)
sedimentary
Lake Superior Agate
Silicon Dioxide (Chalcedony/Quartz), formula SiO2
mineral
Limestone
Calcareous sedimentary rock (CaCO3)
sedimentary
Porphyritic Basalt or Spotted Pebble
Porphyritic volcanic rock with phenocrysts
igneous
Basalt
Extrusive Igneous Rock
igneous
Sandstone
Clastic Sedimentary Rock
sedimentary
Quartzite Pebble
Metamorphic Quartzite
metamorphic
Flint
Sedimentary cryptocrystalline quartz (SiO2)
sedimentary
Flint
SiO2 (Microcrystalline Quartz)
sedimentary
Fossilized Bone
Vertebrate fossil (mineralized bone)
fossil
Quartzite Pebble
Metamorphic Quartzite
metamorphic
Coal
Carbonaceous sedimentary rock / Lignite to Bituminous coal
sedimentary
Flint / Chert Pebble
Microcrystalline quartz (SiO2)
sedimentary
Flint / Chert Nodule
Microcrystalline quartz (SiO2)
sedimentary
Septarian Nodule
Septarian Concretion (Calcite, Aragonite, and Limestone)
sedimentary
Basalt Pebble
Extrusive Igneous Rock
igneous
Jasper
Microcrystalline Quartz (SiO2)
sedimentary
Flint / Chert
Silicon Dioxide (SiO2)
sedimentary
River Pebble
Quartzite / Weathered Sedimentary Rock
sedimentary
Agate
Silicon Dioxide (Chalcedony), SiO2
sedimentary
Quartzite
Metamorphic Quartzite
metamorphic