Agate
Silicon Dioxide (Chalcedony), SiO2
sedimentary
Category
Industrial Byproduct (Anthropogenic Material)
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Obsidian (black volcanic glass)
Obsidian; primarily amorphous SiO₂-rich rhyolitic glass
igneous
Rough White Zircon
Zircon (Zirconium Silicate, ZrSiO4)
mineral
Asphalt (Bituminous Slate/Sandstone)
Asphaltum / Bituminous Rock
sedimentary
Fossilized coral or porous marine limestone
Likely fossil coral (Scleractinia), composed mainly of calcite/aragonite (CaCO₃)
fossil
Basalt
Basalt (Aphanitic Mafic Igneous Rock)
igneous
Tumbled red jasper
Jasper, microcrystalline quartz (SiO₂) colored mainly by iron oxides
mineral
Diamond
Carbon (C)
gemstone
Diamond
Diamond (C)
mineral
Chert (Flint)
Chert (Cryptocrystalline Silica/SiO2)
sedimentary
Rounded yellow-brown pebble
Likely iron-stained sandstone or quartz-rich river cobble
sedimentary
Quartzite
Quartzite (primarily SiO2)
metamorphic
Red jasper (likely brecciated jasper)
Microcrystalline quartz/chalcedony, SiO₂, colored mainly by iron oxides
mineral
Chert / Jasper
Silicon Dioxide (SiO2)
sedimentary
Tumbled chalcedony or quartz-rich stone
Microcrystalline quartz, SiO₂; possibly pale chert or chalcedony
mineral
White quartz in dark matrix (likely quartz-bearing breccia or polished composite specimen)
Quartz, SiO₂, in an unidentified dark silicate matrix
mineral
Orbicular jasper (orbicular chert), likely ocean jasper
Silicified microcrystalline quartz (chalcedony), SiO₂, with iron-oxide and/or clay-rich orbicules
sedimentary
Quartzite Pebble
Metamorphosed Quartz Sandstone (SiO2)
metamorphic
Chalk
Calcium Carbonate (CaCO3)
sedimentary
Basalt
Basalt
igneous
Diamond
Carbon (C)
mineral
Diamond
Carbon (C)
mineral
Weathered river pebble, likely quartz-rich sandstone or iron-stained quartzite
Provisional identification: quartz-rich sandstone/quartzite; exact composition cannot be confirmed from the image
sedimentary
Agate
Silicon Dioxide (Chalcedony), SiO2
sedimentary
Likely weathered fossil bone fragment
Indeterminate fossilized bone; taxonomic identification requires microscopy and locality data
fossil
Quartz-bearing iron-rich rock, possibly quartzite or hydrothermal breccia
Quartz (SiO₂) with iron oxides/hydroxides, likely limonite/goethite; exact host rock is uncertain from the photograph
metamorphic
Amethyst quartz crystal cluster
Quartz, SiO₂; purple coloration from irradiation and trace iron
mineral
Fossilized oyster shell in limestone
Bivalvia fossil; chiefly calcite (CaCO₃)
fossil
Rose quartz
Quartz, silicon dioxide (SiO₂), pink variety
mineral
Red Sandstone
Clastic Sedimentary Rock (typically contains Quartz and Iron Oxide)
sedimentary
Banded Chert
Microcrystalline Quartz (SiO2)
sedimentary
Greenschist
Greenschist (Chlorite-actinolite schist)
metamorphic
Marble
Metamorphosed Limestone (CaCO3)
metamorphic
Corundum (Sapphire variant)
Aluminum Oxide (Al2O3)
mineral
Sandstone (Quartz-rich)
Clastic sedimentary rock (SiO2 primary)
sedimentary
Chalcopyrite (Peacock Ore)
Chalcopyrite (CuFeS2)
mineral
Chert (Nodule)
Microcrystalline Quartz (SiO2)
sedimentary
Red Sandstone
Arenite (Fe2O3 rich)
sedimentary
Sodalite
Sodalite - Na8(Al6Si6O24)Cl2
mineral
Orange Quartzite (River Pebble)
Quartzite (primarily SiO2)
metamorphic
Schist
Mica Schist
metamorphic
Olivine in Basalt (Peridot)
Magnesium Iron Silicate (Mg,Fe)2SiO4 (Mineral) / Scoriaceous Basalt (Host Rock)
igneous