Weathered vuggy quartz-rich rock (probable silicified limestone or quartz breccia)
Microcrystalline quartz (SiO₂) with calcite (CaCO₃), iron oxides, and minor clay minerals
sedimentary
Category
Industrial Byproduct (Anthropogenic Rock)
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Anthracite Coal
Anthracite (Carbon-rich Sedimentary Rock)
sedimentary
Pink Quartzite
Quartzite (primarily SiO2)
metamorphic
Tumbled milky quartz
Quartz (silicon dioxide, SiO₂)
mineral
Schist (Greenschist / Mica Schist)
Metamorphic rock rich in platy minerals (e.g., Chlorite/Mica schist)
metamorphic
Polished brecciated jasper
Jasper, opaque microcrystalline quartz (SiO₂), with iron-oxide and other mineral inclusions
gemstone
Quartzite
Quartzite (SiO2)
metamorphic
Gray Agate
Chalcedony (Silicon Dioxide, SiO2)
mineral
Quartzite
Quartzite (composed primarily of Quartz, SiO2)
metamorphic
Quartzite
Quartzite (SiO2)
metamorphic
Laterite
Laterite (Iron and aluminum-rich residual rock)
sedimentary
Ferruginous Sandstone
Clastic Sedimentary Rock (Sandstone with Iron Oxide cement)
sedimentary
Limestone
Sedimentary rock composed primarily of Calcium Carbonate (CaCO3)
sedimentary
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
Quartzite Pebble
Quartzite (primarily SiO2)
metamorphic
Basalt
Basalt (Mafic volcanic rock, primarily Plagioclase and Pyroxene)
igneous
Quartzite
Quartzite (primarily SiO2)
metamorphic
Desert Rose
Baryte or Gypsum (Selenite) with Sand Inclusions (BaSO4 or CaSO4·2H2O)
mineral
Quartzite
Quartzite (SiO2)
metamorphic
Schist
Mica Schist (Quartz-Muscovite-Biotite Schist)
metamorphic
Quartzite
Quartzite (SiO2)
metamorphic
Agate
Silicon Dioxide (SiO2) - Chalcedony variety
mineral
Tumbled tree agate (dendritic agate)
Cryptocrystalline quartz, SiO₂, with manganese/iron-oxide dendrites
mineral
Sandstone
Arenite (SiO2 + various cementing minerals)
sedimentary
Quartzite
Metamorphic rock primarily composed of Quartz (SiO2)
metamorphic
Quartzite
Quartzite (SiO2)
metamorphic
River Siltstone / Mudstone Pebble
Siltstone (composed of mixed silicate and carbonate minerals)
sedimentary
Schist
Crystalline Schist (often containing Muscovite, Biotte, or Quartz)
metamorphic
Tumbled green jasper (probable)
Jasper, opaque microcrystalline quartz (SiO₂), colored by iron and other impurities
mineral
Blue Sapphire
Corundum (Al2O3)
mineral
Sapphire
Corundum (Al2O3)
mineral
Quartzite (specifically a river-worn cobble)
Quartzite (primarily Silicon Dioxide, SiO2)
metamorphic
Desert Rose (also known as Sand Rose)
Gypsum (CaSO4·2H2O) or Barite (BaSO4) with sand inclusions
mineral
Red Sandstone (Old Red Sandstone Pebble)
Arenite with iron oxide (Fe2O3) cement
sedimentary
Quartzite (or Milky Quartz pebble)
Quartzite (primarily Silicon Dioxide, SiO2)
metamorphic
Quartzite
Quartzite (SiO2)
metamorphic
Pumice
Pumice (a highly vesicular volcanic glass)
igneous
Chert (Jasper/Flint variety)
Silicon Dioxide (SiO2)
sedimentary
Basalt
Basalt (principally composed of pyroxene and plagioclase feldspar)
igneous
Granite
Phaneritic Igneous Rock (composed mostly of Quartz, Feldspar, and Mica)
igneous
Smoky Quartz
Silicon Dioxide (SiO2)
mineral
Quartzite / Sandstone / Chert Mix
Silicon Dioxide (SiO2)
sedimentary and metamorphic