Orthoceras Fossil in Limestone
Orthoceras (extinct genus of cephalopods), mineralized as Calcite (CaCO3) in Fossiliferous Limestone
sedimentary
Category
Organic Structure (Not A Rock)
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Basalt Pebble (Vesicular / Beach Cobble)
Basalt (mafic extrusive igneous rock)
igneous
Yellow Quartzite (River Pebble)
Quartzite (SiO2)
metamorphic
Shale
Fissile mudstone (Shale)
sedimentary
Quartzite
Quartzite (primarily SiO2)
metamorphic
Chert Pebble (with fossil shell fragment)
Microcrystalline Quartz (SiO2) with Calcified Invertebrate Impression
sedimentary
Chert (Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Honey Calcite
Calcium Carbonate (CaCO3)
mineral
Orange Calcite
Calcium Carbonate (CaCO3)
mineral
Pink Opal
Hydrated Silicon Dioxide (SiO2 · nH2O)
mineraloid
Chert (Jasper/Flint variant)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Fossiliferous Limestone (Coquina)
Biogenic Limestone (Calcium Carbonate, CaCO3)
sedimentary
Chert (Jasper/Common Opal transition)
Microcrystalline Quartz (SiO2) with iron oxide inclusions
sedimentary
Mica Schist with Pyrite
Mica Schist (FeS2 containing)
metamorphic
Quartz Vein in Host Rock
Silicon Dioxide (SiO2)
mineral
Quartzite with Calcite Accretion
Metamorphosed Quartz Sandstone (SiO2 with CaCO3 coating)
metamorphic
Dyed Pink Agate
Silicon Dioxide (SiO2) - variety Chalcedony
mineral
Dalmatian Jasper
Peralkaline Quartz-Feldspar Rock with Arfvedsonite
igneous
Chert / Chalcedony (likely carnelian or flint variety)
Silicon Dioxide (SiO2)
sedimentary
Petrified Wood
Silicified wood (Quartz/Chalcedony replacement)
fossil
Fossilized Wood (Petrified Wood)
Silicified Wood (primarily quartz/chalcedony replacing organic matter)
Sedimentary (with some aspects of mineral replacement)
Basalt with Quartz/Calcite Veins
Basalt with hydrothermal vein infill
igneous
Basalt
Basalt (Aphanitic Mafic Igneous Rock)
igneous
Shale
Shale (claystone/mudstone)
sedimentary
Quartz Veined Basalt
Mafic Volcanic Rock with Microcrystalline Quartz (SiO2)
igneous
Moss Agate
Silicon Dioxide (SiO2) with inclusions of Manganese or Iron oxide
mineral
Amber / Copal
Succinite (fossilized resin)
mineraloid
Fossilized Sand Tiger Shark Tooth
Carcharias taurus / Striatolamia macrota (mineralized as Hydroxylapatite/Francolite)
sedimentary (fossil)
Chert (specifically Jasper or Flint type)
Microcrystalline Quartz (SiO2)
sedimentary
Sandstone (likely Graywacke or Arkosic varieties)
Arenite (composed primarily of SiO2)
sedimentary
Petrified Wood
Silicified Wood (SiO2)
fossil
Granite / Quartzite Specimen
Granite / Quartz (SiO2 with Feldspar and Mica)
igneous
Chert (Jasper/Flint variety)
Microcrystalline Quartz (SiO2)
sedimentary
Petrified wood
Silicified wood, chiefly microcrystalline quartz (SiO₂)
fossil
Basalt
Extrusive Igneous Rock
igneous
Shale
Shale (clastic sedimentary rock composed of silt and clay-sized particles)
sedimentary
Crazy Lace Agate
Microcrystalline Quartz (SiO2)
sedimentary
Petrified Wood
Silicified Wood / Xylopal
fossil
Quartz Geode
Silicon Dioxide (SiO2) within a sedimentary or volcanic shell
mineral
Sandstone Cobble
Clastic Sedimentary (Sandstone)
sedimentary
Sandstone
Arenite
sedimentary
Amber (or polished Chalcedony bead)
Fossilized Tree Resin / SiO2 (Silicon Dioxide if Chalcedony)
gemstone