Weathered sandstone or arkosic sandstone
Clastic sandstone, likely quartz–feldspar-rich (arkose)
sedimentary
Category
Sedimentary Or Igneous (Host Environment)
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Garnet-bearing metamorphic rock, likely garnet schist or amphibolite
Almandine garnet (Fe₃Al₂Si₃O₁₂) in mica- or amphibole-rich matrix
metamorphic
Smoky Quartz with Hematite inclusions
Silicon Dioxide (SiO2) with Fe2O3 inclusions
mineral
Quartz Vein in Host Rock
Silicon Dioxide (SiO2) in matrix
mineral
Quartz (specifically Clear Quartz or Rock Crystal)
Silicon Dioxide (SiO2)
mineral
Milky Quartz
Silicon Dioxide (SiO2)
mineral
Chert (specifically Flint Arrowhead)
Silicon dioxide (SiO2) - Microcrystalline Quartz
sedimentary
Magnetite
Magnetite (Fe3O4)
mineral
Chert in Limestone (or Flint Nodule)
Silicon Dioxide (SiO2) within Calcium Carbonate (CaCO3)
sedimentary
Dolomite or Limestone (Carbonate Rock)
CaMg(CO3)2 (Dolomite) or CaCO3 (Limestone / Calcite)
sedimentary
Chert
Microcrystalline Quartz (SiO2)
sedimentary
Fossilized Shark Tooth in Matrix
Otodus sp. (likely Otodus obliquus)
sedimentary
Milky Quartz
Silicon Dioxide (SiO2)
mineral
Weathered, quartz-rich metamorphic rock (likely schist or gneiss)
Quartz–feldspar–mica schist/gneiss, with surface lichens and iron-oxide staining
metamorphic
Milky Quartz with Iron Oxide Weathering
Silicon Dioxide (SiO2) with Goethite/Limonite coatings
mineral
Gneiss (Granitic Gneiss)
Gneiss (composed primarily of Quartz, Feldspar, and Mica)
metamorphic
Milky Quartz with Iron Staining
Quartz (Silicon Dioxide, SiO2)
mineral
Chalcedony (Agate)
Silicon Dioxide (SiO2)
mineral
Gneiss (Gneissic Granite Pebble)
Metamorphic rock rich in Quartz, Feldspar, and Mica
metamorphic
River Pebble (Gneiss or Quartzite variant)
Metamorphic rock specimen (likely Quartzite or Gneiss)
metamorphic
Turquoise
CuAl6(PO4)4(OH)8·4H2O
mineral
Basalt with Mineral Vein (Cobble)
Basalt (with likely Quartz/Calcite vein)
Igneous
K2 Jasper (K2 Granite)
Azurite in Granite (Biotite Granite with Azurite inclusions)
igneous
Pyrite in Matrix
Iron Sulfide (FeS2) embedded in host rock
mineral
Pebble (likely Quartz or Chert)
SiO₂ (Silicon Dioxide) - referring to the likely main mineral composition, Quartz. If it's chert, the scientific name remains SiO₂ with a microcrystalline structure.
Sedimentary Rock
Eudialyte in Matrix
Na15Ca6Fe3Zr3Si26O72(OH,Cl,H2O)3
mineral
Botryoidal Pyrite
Iron Sulfide (FeS2)
mineral
Probable magnetite-bearing rock
Magnetite (Fe₃O₄), possibly in a fine-grained host rock
mineral
Calcite
Calcite (calcium carbonate, CaCO₃), likely a massive crystalline specimen
mineral
Almandine Garnet
Almandine, Fe3Al2(SiO4)3
mineral
Labradorite (a variety of Feldspar)
Labradorite; (Na,Ca)(Al,Si)4O8 (a plagioclase feldspar)
igneous
Chert Pebble with Quartz Vein
Microcrystalline Quartz (SiO2)
sedimentary
Milky quartz–rich rock
Quartz (SiO₂), likely massive milky quartz with minor dark inclusions
mineral
Jasper with Quartz Vein
Microcrystalline quartz (SiO2) and chalcedony with a quartz vein
sedimentary
Carnelian
Carnelian (Chalcedony / SiO2)
mineral
Chert (Nodular)
Microcrystalline Silica (SiO2)
sedimentary
Plume Agate
Silicon Dioxide (SiO2)
mineral
Cryptocrystalline Quartz (Agate/Chert)
Silicon dioxide (SiO2)
sedimentary
Quartz with Host Rock
Silicon Dioxide (SiO2)
mineral
Quartz (Vein Quartz)
Silicon Dioxide (SiO2)
mineral
Manganese Oxide Crust on Limestone
Manganese Oxides (e.g., Pyrolusite MnO2 or Romanechite) on CaCO3
sedimentary
Veined Limestone (or Quartz-Veined Slate/Shale)
Metamorphosed Sedimentary Rock with Calcite/Quartz Veins
metamorphic