Fossiliferous Limestone
Carbonate Sedimentary Rock (primarily CaCO3)
sedimentary
Category
Not A Rock (Synthetic Material)
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Ferruginous Sandstone (Ironstone)
Ferruginous arenite
sedimentary
Granite Water-Worn Pebble
Intermediate to Felsic Plutonic Rock (Granite)
igneous
Chert / Jasper
Microcrystalline Quartz (SiO2)
sedimentary
Likely basalt fragment
Basalt; fine-grained mafic volcanic rock, chiefly plagioclase and pyroxene with possible olivine
igneous
Basalt
Basalt (Mafic volcanic rock)
igneous
Basalt
Extrusive mafic igneous rock
igneous
Vesicular Basalt
Mafic Volcanic Rock (Basalt)
igneous
Chert (Flint)
Chert (Cryptocrystalline Silica, SiO2)
sedimentary
Cullet Glass (Slag Glass)
Amorphous Silicon Dioxide (SiO2) with metallic oxide impurities
mineraloid
Chert (Jasper/Flint variety)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Jasper)
Silicon Dioxide (SiO2)
sedimentary
Banded Chert
Microcrystalline silicon dioxide (SiO2)
sedimentary
Chert (Flint)
Silicon dioxide (SiO2)
sedimentary
Granite
Phaneritic Felsic Igneous Rock
igneous
Slate
Slate (Foliated Metamorphic Rock)
metamorphic
Orange chalcedony or weathered quartz pebble
Microcrystalline quartz, SiO₂; possibly iron-oxide-stained chalcedony
mineral
Likely quartzite pebble
Quartzite, predominantly crystalline SiO₂
metamorphic
Red Jasper
Jasper (Silicon Dioxide, SiO2 with Fe2O3 inclusions)
mineral
Coquina
Biogenic Limestone (Calcium Carbonate, CaCO3)
sedimentary
Apache Tear (Obsidian)
Obsidian (Hydrated Amorphous Silica, SiO2 + MgO/Fe3O4)
igneous
Shale with Trace Fossils
Fissile mudrock (Shale)
sedimentary
Unakite
Unakitized granodiorite / Quartz-Epidote-Feldspar rock
metamorphic
Pink Granite
Phaneritic Felsic Igneous Rock (Granite)
igneous
Quartzite
Metamorphic Quartzite (SiO2)
metamorphic
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Sandstone (Quartzite-rich)
Clastic sedimentary rock (SiO2 primary)
sedimentary
Chert (specifically Pink/Tan Chert)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Mixed river-worn rock and mineral collection
Mostly quartz/quartzite, feldspar-bearing granitoid, chert, and mafic volcanic rocks; exact species vary by pebble
igneous, sedimentary, metamorphic, mineral
Quartz-rich metamorphic rock (likely mica schist or gneiss)
Quartz–feldspar–mica assemblage; probable biotite schist/gneiss
metamorphic
Snowflake Obsidian
Volcanic glass containing Spherulitic Cristobalite (SiO2)
igneous
Black tumbled stone, likely basalt or black jasper
Most consistent with fine-grained basalt (mainly plagioclase and pyroxene); exact identification requires testing
igneous
Limestone
Sedimentary Calcium Carbonate (CaCO3)
sedimentary
Sandstone (likely Ferruginous)
Arenite with Iron Oxide cement
sedimentary
Red Sandstone
Arenite with iron oxide (Hematite) cement
sedimentary
Quartzite
Quartzite (principally SiO2)
metamorphic
Sandstone (Red)
Arenite (Fe2O3 heavy)
sedimentary
Sandstone
Arenite (SiO2 principal component)
sedimentary
Sandstone (Quartz-rich)
Arenite (SiO2)
sedimentary
Breccia
Breccia (Clastic Sedimentary Rock)
sedimentary
Granite
Phaneritic Felsic Igneous Rock
igneous
Conglomerate (or Breccia)
Clastic Sedimentary Rock (Conglomeratic)
sedimentary