Basalt
Mafic extrusive igneous rock
igneous
Category
Not A Rock (Man Made Polymer)
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Herkimer Diamond
Quartz (Silica - SiO2)
mineral
Shale
Shale (Fine-grained clastic sedimentary rock)
sedimentary
Vuggy Quartz on Matrix
Crystalline Silicon Dioxide (SiO2)
mineral
River Rocks (Black)
Various lithologies (e.g., basalt, chert, obsidian for black varieties), mechanically rounded clasts
Sedimentary
Coal
Coal (Sedimentary Rock / Organic Rock)
sedimentary
Sandstone (with potentially high Feldspar/Arkose content)
Clastic sedimentary rock (SiO2 dominated)
sedimentary
Granite
Granite
Igneous
Weathered garnet-bearing gneiss
Quartz–feldspar–mica gneiss with almandine garnet, chiefly Fe₃Al₂(SiO₄)₃
metamorphic
Quartz Vein in Matrix
Silicon Dioxide (SiO2) within Rhyolitic or Granitic Matrix
igneous
Basalt Pebble
Extrusive Igneous Rock (Mafic)
igneous
Granite
Intrusive Igneous Rock
igneous
Shale with Quartz Veins
Fissile Sedimentary Rock (SiO2)
sedimentary
Basalt
Extrusive mafic igneous rock
igneous
Breciated Jasper
Silicon Dioxide (SiO2) with iron oxide inclusions
sedimentary
Hag Stone (Adder Stone / Geode-bearing Pebble)
Sedimentary Rock with Cavity (often Quartzite, Limestone, or Sandstone)
sedimentary
Sandstone (with Iron Staining)
Arenite (primarily SiO2 with Fe2O3/FeO(OH) oxides)
sedimentary
Vesicular Basalt with Quartz/Chalcedony
Vesicular Basalt (primarily Plagioclase, Pyroxene, and Olivine with SiO2 infill)
igneous
Basalt
Extrusive mafic igneous rock
igneous
Basalt with Quartz/Calcite Veining
Basalt (principally Plagioclase and Pyroxene)
igneous
Granite
Granite
Igneous
Druzy Quartz on Matrix
Silicon Dioxide (SiO2)
mineral
Weathered Sandstone or Siltstone
Sedimentary Rock
sedimentary
Orbicular granite (likely rapakivi-type granite)
Granite; chiefly quartz, alkali feldspar, plagioclase, and biotite/hornblende
igneous
Slickenside
Tectonic Fault Scarp Surface
metamorphic
Basalt
Extrusive Igneous Rock
igneous
Basalt
Mafic Igneous Rock (composed primarily of pyroxene and calcium-rich plagioclase)
igneous
Basalt pebble
Aphanitic Mafic Volcanic Rock (Fe/Mg rich)
igneous
Quartz Vein in Host Rock
Hydrothermal Quartz (SiO2) in Slates/Schists
metamorphic
Sandstone (Quartzose)
Arenite (primarily SiO2)
sedimentary
Quartz-rich mineral fragment
Quartz (silicon dioxide, SiO₂), possibly milky quartz
mineral
Sedimentary Rock with Crafts (Pet Rock)
Sedimentary rock decorated with synthetic materials
sedimentary
Shale
Lutaceous sedimentary rock
sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Eclogite
Eclogite (High-pressure metamorphic rock)
metamorphic
Basalt with Quartz Veins
Aphanitic Mafic Igneous Rock (Main body: SiO2, Fe, Mg rich)
igneous
Rugose Coral Fossil
Order Rugosa
fossil
Weathered granitic rock
Granite, likely quartz–feldspar–mica aggregate
igneous
Fossil Shell
Invertebrate fossil (Mollusca)
fossil
Sandstone Pebble / Quartzite Pebble
SiO2 (Silicon Dioxide enriched sedimentary rock)
sedimentary
Chalcedony Geode
Silicon Dioxide (SiO2)
mineral
Basalt
Extrusive igneous rock primarily composed of plagioclase feldspar and pyroxene
igneous