Basalt Pebble
Aphanitic mafic volcanic rock
Category
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Basalt Pebble
Aphanitic mafic volcanic rock
River Stone (likely Mudstone or Siltstone)
Lutite (Clastic sedimentary rock composed of clay and silt-sized particles)
Ferruginous Sandstone (with possible trace fossils)
Arenite with Iron-Oxide Cement (SiO2 with Fe2O3)
Blue Lace Agate
Silicon Dioxide (SiO₂), a variety of Chalcedony
Sandstone (specifically Red Sandstone)
Arenite (SiO2 with Iron Oxide)
Limonite
Limonite (FeOO·nH2O)
Blue Tiger's Eye
Silicon Dioxide (SiO2) with Crocidolite inclusions
Amethyst
Silicon Dioxide (SiO2) with iron impurities
Grey Agate (Banded Chalcedony)
Agate (Silicon Dioxide - SiO2)
River Quartz Pitting/Cobble
Silicon Dioxide (SiO2)
Amethyst
Amethyst (Silicon Dioxide, SiO2 with Iron impurities)
Chert (Jasper)
Silicon Dioxide (SiO2)
Basalt
Mafic Volcanic Rock (primarily Plagioclase and Pyroxene)
Shale
Shale
Orbicular Granite
Orbicular Granitoid
Golden Sheen Obsidian
Obsidian (volcanic glass) with inclusions of gas bubbles and mineral crystals (e.g., hematite, magnetite) causing the sheen
Sandstone (Quartzose)
Arenite (primarily SiO2)
Unakite
Unakite (Metasomatized Granite)
Petrified Wood
Silicified wood (principally Silicon Dioxide, SiO2)
Sandstone (Quartzose)
Arenite (primarily SiO2)
Vesuvianite (Idocrase)
Ca19(Al, Mg, Fe)13(SiO4)10(Si2O7)4(OH, F, O)10
Breccia
Clastic Breccia (General mineral composition depends on fragments, often SiO2 or CaCO3)
Chert (Common Opal/Jasper variety)
Cryptocrystalline Quartz (SiO2)
Milky Quartz
Silicon Dioxide (SiO2)
Limonite Concretion
Limonite (FeO(OH)·nH2O)
Moss Agate
Silicon Dioxide with inclusions (SiO2 + impurities)
Pyrite
Iron Sulfide (FeS2)
Quartz Druzy Geode
Silicon Dioxide (SiO2) - Crystalline Variety
Smoky Quartz
Silicon Dioxide (SiO2)
Charoite
Charoite (Hydrated potassium sodium calcium barium strontium silicate hydroxyfluoride)
Sandstone (Ferruginous)
Arenite (Iron-rich)
Sandstone (Ferruginous)
Arenite (Fe2O3 dominant staining)
Sandstone
Arenite (Sedimentary rock composed of sand-sized minerals or rock grains)
Rock Salt / Halite Crust
Halite (Sodium Chloride, NaCl)
Gneiss (Granitic Gneiss)
Gneiss
Amethyst Quartz with Matrix
Silicon Dioxide (SiO2)
Chert (Field Stone/Pebble)
Microcrystalline or cryptocrystalline Quartz (SiO2)
Jasper
Jasper (Silicate - SiO2)
Fluorite
Fluorite (Calcium Fluoride - CaF2)
Magnetite / Iron Ore
Magnetite (Fe3O4)
Quartz (specifically Clear Quartz or Rock Crystal)
Silicon Dioxide (SiO2)
Amethyst
Silicon Dioxide with iron impurities (SiO2)