Chert (and/or Flint)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Category
Synthetic (Man Made Material Mimicking Natural Stone)
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Sandstone (Quartzose)
Arenite (primarily SiO2)
sedimentary
Tumbled green jasper (probable serpentine-rich stone)
Jasper, microcrystalline quartz (SiO₂), possibly mixed with serpentine or chlorite
mineral
Black Tourmaline (Schorl)
Schorl (Na(Fe²⁺)₃Al₆(BO₃)₃Si₆O₁₈(OH)₄)
mineral
Sandstone
Arenite (composed primarily of SiO2)
sedimentary
Pink Sapphire
Corundum (Al2O3 with trace Chromium and Iron)
mineral
Granite
Intrusive Igneous Rock
igneous
Basalt (Greenstone/Water-worn Pebble)
Basalt (containing Chlorite/Epidote)
igneous
Chert (Flint/Chalcedony)
Silicon Dioxide (SiO2)
sedimentary
Greenstone / serpentinite carving
Serpentinite, chiefly serpentine-group minerals (antigorite, lizardite, or chrysotile); exact identification requires testing
metamorphic
Sandstone
Sedimentary Rock (Quartz arenite / Lithic sandstone)
sedimentary
Sandstone
Arenite
sedimentary
Sandstone
Arenite (SiO2 primarily)
sedimentary
Chalcedony (Agate / Jasper Specimen)
Silicon Dioxide (SiO2)
mineral
Ruby (set in a gold pendant)
Ruby (Variety of Corundum, Al2O3)
mineral
Sandstone
Clastic Sedimentary Rock
sedimentary
Diamond
Natural Diamond (Carbon, C)
gemstone
Sandstone
Sedimentary quartz arenite
sedimentary
Sandstone
Clastic Sedimentary Rock
sedimentary
Tumbled white quartz pebble
Quartz (silicon dioxide, SiO₂)
mineral
Tumbled purple quartz, likely amethyst or lavender quartz
Quartz (SiO₂), probably iron-colored amethyst; exact variety uncertain from the image
mineral
Hag Stone
Perforated Sedimentary Rock (typically Limestone or Sandstone)
sedimentary
Chert
Microcrystalline Silicon Dioxide (SiO2)
sedimentary
Chert (varietal Chalcedony or Flint)
Silicon dioxide (SiO2) - Microcrystalline Quartz
sedimentary
Sandstone
Quartz Arenite / Clastic Sedimentary Rock
sedimentary
Sandstone
Arenite (SiO2 primarily)
sedimentary
Pink Granite
Granite (composed of Potassium Feldspar, Quartz, and Plagioclase)
igneous
Sandstone
Arenite
sedimentary
Diamond (or Diamond Simulant)
Carbon (C)
mineral
Coquina or Fossiliferous Conglomerate
Bioclastic Rudstone (variable composition)
sedimentary
Sandstone with Liesegang Rings
Arenite with Iron Oxide Liesegang Banding
sedimentary
Chert (often called Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Tumbled purple quartz, likely amethyst
Quartz (SiO₂), purple variety commonly colored by iron impurities and irradiation
mineral
Weathered, porous limestone (probable fossiliferous limestone)
Calcite-rich limestone; predominantly CaCO₃
sedimentary
Agate (specifically, multi-colored or pastel-dyed agate)
Silicon dioxide (SiO2) - specifically, a cryptocrystalline variety of quartz known as Chalcedony, with banding classified as Agate. (If it were Fluorite, the chemical formula would be Calcium Fluoride - CaF2).
Mineral
Chert
Microcrystalline Quartz (SiO2)
sedimentary
Chert / Green Jasper
Silicon Dioxide (SiO2)
sedimentary
Chert / Flint
Silicon dioxide (Microcrystalline Quartz, $SiO_2$)
sedimentary
Chert (varietal Flint)
Microcrystalline quartz (SiO2)
sedimentary
Weathered quartz-rich pebble, possibly granitic gneiss
Quartz–feldspar–mica aggregate; likely granitoid or gneiss
metamorphic
Sandstone (Ferruginous)
Clastic Sedimentary Rock (SiO2 with Fe2O3)
sedimentary
Polished blue calcite sphere (tentative identification)
Calcite, CaCO₃; blue color generally results from trace impurities or inclusions
mineral