Sandstone (Quartzose)
Arenite (primarily SiO2)
sedimentary
Category
Man Made
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Granite
Granite (Mainly Quartz SiO2, Feldspar KAlSi3O8, and Mica KAl2(AlSi3O10)(OH)2)
Igneous
Quartz Sandstone Pebble
Sandstone (SiO2 dominated)
sedimentary
Quartzite
Metamorphic Rock (Mainly SiO2)
metamorphic
Likely iron-rich rock or weathered metallic mineral fragment
Uncertain; possibly limonite/goethite or iron-bearing slag
mineral
Dark gray rounded stone, possibly basalt or slag
Uncertain; likely fine-grained basalt (plagioclase–pyroxene) or iron-rich industrial slag
igneous
Aura Quartz (Anomalously Coated Quartz)
Silicon Dioxide (SiO2) treated with vaporized metals
mineral
Sandstone
Clastic Sedimentary Rock
sedimentary
Sandstone (Quartzose)
Sandstone (SiO2 dominated)
sedimentary
Chert (Flint)
Silicon Dioxide (SiO2)
sedimentary
Weathered chert or chalcedony nodule
Microcrystalline quartz (SiO₂), possibly silicified limestone or agate-like chalcedony
sedimentary
Brecciated Jasper
Silicon Dioxide (SiO2) with iron oxide inclusions
sedimentary
Pearl and Garnet Glass
Calcium Carbonate (CaCO3) for pearl; Silicon Dioxide (SiO2) for glass
mineral and glass
Smoky Quartz
Smoky Quartz (SiO2)
mineral
Pearl
Organic gemstone (Calcium carbonate - CaCO3)
mineral
Diamond
Carbon (C)
mineral
Diamond
Carbon (C)
gemstone
Chert
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Siltstone / Flint)
SiO2 (Cryptocrystalline Quartz)
sedimentary
Banded Jasper / Chert Beach Pebble
Microcrystalline Quartz (SiO2)
sedimentary
Chert
Microcrystalline Quartz (SiO2)
sedimentary
Chert / Flint
Silicon Dioxide (Microcrystalline Quartz, SiO2)
sedimentary
Green Quartzite
Metamorphic Quartzite (often colored by chromium-bearing minerals or fuchsite)
metamorphic
Flint / Chert
Microcrystalline quartz (SiO2)
sedimentary
Quartzite
Metamorphic Quartzite (SiO2)
metamorphic
Pearl
Calcium carbonate (CaCO3) - mainly Aragonite with Conchiolin
mineraloid
Chert (specifically Flint or Nodular Chert)
Silicon dioxide (SiO2)
sedimentary
Diamond (in a jewelry setting)
Cubic Carbon (C)
mineral
Petrified Wood
Silicified Wood (SiO2)
sedimentary
Sandstone
Arenite (composed primarily of SiO2)
sedimentary
Chalk
Carbonate rock (mainly CaCO3)
sedimentary
Granodiorite
Granodiorite (phaneritic intrusive igneous rock)
igneous
Chert (Jasper/Flint var.)
Silicon Dioxide (SiO2)
sedimentary
Obsidian
Volcanic Glass (SiO2)
igneous
Chert (often called Flint or River Stone)
Microcrystalline alpha-quartz (SiO2)
sedimentary
Chert (Flint)
Silicon Dioxide (SiO2)
sedimentary
Chert (Flint)
Silicon Dioxide (SiO2)
sedimentary
Red Jasper
Silicon Dioxide (SiO2) with Hematite (Fe2O3)
sedimentary
Chert (Chert / Flint Variety)
Microcrystalline / Cryptocrystalline Quartz (SiO2)
sedimentary
Likely clear quartz crystal (possibly cut/polished quartz or glass imitation)
Quartz, silicon dioxide (SiO₂)
mineral
Granite
Granite (a plutonic rock)
Igneous
Polished agate bead bracelet
Agate, a banded microcrystalline variety of quartz (SiO₂), likely mixed-color dyed or naturally colored chalcedony
gemstone