Small rounded pebble, likely quartz-rich sandstone or granitic fragment
Indeterminate lithic clast; possible quartz–feldspar aggregate
igneous
Category
Sedimentary Or Igneous (Host Environment)
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Geode
Quartz nodule / Chalcedony-lined cavity
sedimentary
Quartz
Silicon Dioxide (SiO2)
mineral
Quartz Cluster (Likely Ferruginous)
Silicon Dioxide (SiO2)
mineral
Prehnite with Epidote and Quartz
Prehnite (Ca2Al(AlSi3O10)(OH)2)
mineral
Mica-rich schist (likely quartz-mica schist)
Quartz–mica schist, commonly containing muscovite and/or biotite with quartz and feldspar
metamorphic
Chert on Volcanic Host Rock
Sedimentary Chert (SiO2) within Basalt or Andesite
sedimentary
Quartz Drusy on Matrix
Silicon Dioxide (SiO2)
mineral
Common Opal
Hydrated Amorphous Silica (SiO2·nH2O)
mineraloid
Fluorite in Matrix
Calcium Fluoride (CaF2) with Quartz/Calcite matrix
mineral
Quartz (Milky/Clear)
Silicon Dioxide (SiO2)
mineral
Basalt cobble
Basalt, a fine-grained mafic volcanic rock composed chiefly of plagioclase feldspar and pyroxene, commonly with minor olivine and iron-titanium oxides
igneous
Yellow Jasper
Silicon Dioxide (SiO2)
sedimentary
Quartz Crystal
Silicon Dioxide (SiO2)
mineral
Chalcedony (Agate/Carnelian variant)
Cryptocrystalline Silica (SiO2)
mineral
Quartz Vein in Schist
Quartz-rich Micaceous Schist (SiO2 + phyllosilicates)
metamorphic
Jasper / Agate
Silicon dioxide (SiO2)
sedimentary
Garnet Gneiss or Mica Schist with Garnet
Almandine Garnet-bearing Gneiss
metamorphic
Quartz (Chert/Chalcedony variety)
Silicon Dioxide (SiO2)
mineral
Likely mica schist
Mica-rich schist, probably muscovite–biotite schist
metamorphic
Milky Quartz with Iron Inclusions
Quartz (Silicon Dioxide, SiO2)
mineral
Copper-Bearing Sulfide Ore (likely Chalcopyrite or Bornite)
Chalcopyrite (CuFeS2) or Bornite (Cu5FeS4) in host rock
mineral
Quartz (Druzy)
Silicon Dioxide (SiO2)
mineral
Polished garnet-bearing metamorphic rock
Likely garnet mica schist or garnet-bearing gneiss; garnet is commonly almandine, Fe₃Al₂(SiO₄)₃
metamorphic
Garnet-bearing schist or gneiss
Garnet-mica schist/gneiss; chiefly quartz, feldspar, mica, and almandine–pyrope garnet
metamorphic
Weathered quartz-rich metamorphic rock, likely gneiss or quartzite
Quartz (SiO₂)-bearing gneiss; exact identification requires a fresh surface and tests
metamorphic
Milky Quartz
Quartz (Silica / Silicon Dioxide), SiO2
mineral
Quartz Crystal
Silicon Dioxide (SiO2)
mineral
Gneiss
Gneiss (Metamorphic Rock)
metamorphic
Common Opal in Host Rock
Hydrated Silica (SiO2·nH2O)
mineraloid
Fossiliferous Rock (Invertebrate Fossil in Matrix)
Fossiliferous limestone or shaly matrix containing skeletal fossil remains
fossil
Sapphire
Corundum (Al2O3) with traces of Iron and Titanium
gemstone
Banded gneiss pebble
Gneiss, commonly quartz–feldspar–mica gneiss
metamorphic
Garnet-bearing metamorphic rock, likely garnet gneiss or garnet amphibolite
Garnet-bearing gneiss; red crystals likely almandine garnet, Fe₃Al₂(SiO₄)₃
metamorphic
Quartz-veined Diabase or Basalt Pebble
Diabase or Basalt with Hydrothermal Quartz Veins (SiO2)
igneous
Quartz
Silicon dioxide (SiO2)
mineral
Quartz-veined Gneiss
Gneiss with Quartz (SiO2) intrusions
metamorphic
Eudialyte
Na15Ca6Fe3Zr3Si(Si25O73)(O,OH,H2O)3(Cl,OH)2
mineral
Amethyst
Amethyst (Silicon Dioxide, SiO2)
mineral
Vein Quartz in Basalt or Mafic Rock
Silicon Dioxide (Quartz veins in volcanic host rock)
igneous
Agate in Matrix
Silicon Dioxide (SiO2) within host rock
mineral
Quartz pebble
Silicon Dioxide (SiO2)
sedimentary