Sandstone
Arenite (primarily SiO2)
sedimentary
Category
Anthropogenic (Man Made Material Processed By Nature)
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Sodalite beads
Sodalite, Na₈(Al₆Si₆O₂₄)Cl₂
mineral
Sandstone
Sandstone (arenite is a more specific geological term for a clean sandstone, while wacke refers to a dirty sandstone with significant matrix)
Sedimentary
Quartzite Pebble
Quartzite
metamorphic
Likely black beach pebble
Undetermined; possibly basalt, chert, or dark slate
sedimentary
Petrified Wood
Silicified Wood (primarily SiO2)
sedimentary
Petrified Wood
Silicified wood (primarily Silicon Dioxide, SiO2)
metamorphic
Green Moss Agate
Silicon Dioxide with inclusions (SiO2)
sedimentary
Quartzite
Quartzite (SiO2)
metamorphic
Quartz (Iron-stained)
Silicon Dioxide (SiO2)
mineral
Quartzite
Quartzite
Metamorphic rock
Chert (Flint nodule)
Silicon dioxide (SiO2)
sedimentary
Sandstone (with Iron Staining)
Clastic sedimentary rock (primarily Quartz with Fe2O3 staining)
sedimentary
Serpentinite
Serpentinite (Mg, Fe, Ni, Al, Zn, Mn)2-3(Si, Al, Fe)2O5(OH)4
metamorphic
Serpentine (Serpentinite)
Hydrous magnesium iron silicate, (Mg,Fe)3Si2O5(OH)4
metamorphic
Quartz Pebble
Silicon dioxide (SiO2)
mineral
Chert Pebble/Nodule
Chert (a microcrystalline or cryptocrystalline sedimentary form of quartz, SiO2)
Sedimentary
Tumbled yellow jasper or serpentine
Jasper: microcrystalline quartz (SiO₂); possible serpentine: Mg₃Si₂O₅(OH)₄
mineral
Petrified Wood
Silicified Wood (SiO2)
fossil
Red Jasper
Jasper (Silicon Dioxide, SiO2)
sedimentary
Petrified Wood
Silicified Wood (SiO2)
sedimentary
Petrified Wood
Silicified Wood (SiO2)
metamorphic
Serpentine (Serpentinite)
Serpentinite (complex silicate group including lizardite, chrysotile, and antigorite)
metamorphic
Tiger's Eye
Pseudomorph of Quartz after Crocidolite (SiO2 with inclusions of Iron Oxide)
metamorphic
Serpentinite
Serpentinite (composed primarily of Serpentine group minerals, Mg3Si2O5(OH)4)
metamorphic
Sandstone
Sandstone (various mineral compositions)
Sedimentary
Petrified Wood
Silicified wood (principally SiO2)
sedimentary
Quartzite
Quartzite (composed primarily of SiO2)
metamorphic
Tiger's Eye
Pseudomorph of Quartz after Crocidolite (SiO2)
metamorphic
Iron-stained quartz-rich rock, possibly quartzite or hydrothermal quartz
Quartz (SiO₂), likely with iron oxides; exact host rock uncertain from the photograph
metamorphic
Milky Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Blue Lepidolite
Lepidolite (K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2)
mineral
Serpentinite
Serpentinite (Mg, Fe, Ni, Al, Zn, Mn)2-3(Si, Al, Fe)2O5(OH)4
metamorphic
Yellow Calcite
Calcite (Calcium Carbonate, CaCO3)
mineral
Petrified Wood
Silicified wood (primarily SiO2)
fossil
Chert / Flint
Silicon dioxide (SiO2)
sedimentary
Biotite (Mica)
Biotite (K(Mg,Fe)3AlSi3O10(OH,F)2)
mineral
Greenstone with Epidote or Quartz veins
Metabasalt (Greenstone facies)
metamorphic
Basalt River Stone
Basalt (Aphanitic Mafic Igneous Rock)
igneous
Diamond (Green tinted)
Carbon (C) with trace impurities or lattice defects
mineral
Olivine (Peridot in gem form)
Magnesium Iron Silicate (Mg,Fe)2SiO4
mineral
Chert (specifically Gray/Black Chert)
Chert (Microcrystalline or Cryptocrystalline Quartz, SiO2)
sedimentary