Antropogenic Rock (Man Made)

Quartz (Milky/Crystalline)

Silicon Dioxide (SiO2)

Quartz Geode

Quartz (Silicon Dioxide - SiO2) within a Chalcedony and Limonite shell

Schist

Mica Schist (Medium-grade Metamorphic Rock)

Limonite (after Pyrite Pseudomorph)

Limonite (Hydrated Iron Oxide Mixture, FeO(OH)·nH2O)

White Topaz

Aluminum Silicate Fluoride Hydroxide; Al2SiO4(F,OH)2

Limestone (specifically Travertine or Tufa)

Calcium Carbonate (CaCO3)

Crushed Stone (Basalt/Gabbro)

Mafic Igneous Rock (primarily Plagioclase and Pyroxene)

Agate

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Agate (Common Chalcedony)

Silicon Dioxide (SiO2)

Granite

Phaneritic Plutonic Igneous Rock (primarily composed of quartz, alkali feldspar, and plagioclase)

Massive Quartz with Host Rock

Silicon Dioxide (SiO2)

Concretion

Various mineral compositions, typically carbonate or iron oxide cemented sediment

Sandstone (Iron-stained)

Arenite (composed primarily of SiO2 with Fe2O3 staining)

Agate Geode with Quartz Druzy

Chalcedony (SiO2) and Quartz (SiO2)

Amethyst

Silicon Dioxide (SiO2) with Iron impurities

Banded Sandstone

Arenite with Liesegang banding (primarily SiO2 with FeO(OH) impurities)

Chert (Arrowhead)

Chert (primarily Microcrystalline Silica, SiO2)

Quartz Geode

Silicon Dioxide (SiO2) within a geode

Serpentine

Antigorite, Lizardite, or Chrysotile (Mg,Fe,Ni,Al,Zn,Mn)2-3(Si,Al,Fe)2O5(OH)4

Metaconglomerate

Protolith: Conglomerate (comprising SiO2, Al2O3, etc.)

K2 Jasper (Beads)

Granodiorite with Azurite and Malachite

Banded Gneiss

Gneiss (high-grade metamorphic silicate rock)

Porphyritic Basalt

Basalt (with plagioclase phenocrysts)

Sandstone

Arenite

Smoky Quartz

Smoky Quartz (SiO2)

Sandstone (likely Quartzose Sandstone)

Arenite (SiO2 based)

Tiger's Iron

Pseudomorphic Quartz Aggregate (contains SiO2 with Fe2O3 and FeOOH)

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety, likely a orthogneiss or paragneiss depending on parent rock)

Sandstone or Limestone

Sedimentary Rock

Pebble (Likely Basalt or Siltstone)

Clastic sedimentary rock or mafic volcanic rock

Chert (Iron-Stained)

Microcrystalline Silica (SiO2)

Desert Varnish (on Sandstone)

Rock Varnish (composed of Manganese oxides, Iron oxides, and Clay minerals)

Quartz (Milky Quartz vein fragment)

Silicon Dioxide (SiO2)

Basalt

Mafic volcanic rock (primarily plagioclase feldspar and pyroxene)

Quartz on Matrix

Silicon Dioxide (SiO2)

Quartz (on matrix)

Quartz (Silicon Dioxide, SiO₂)

Smoky Quartz

Silicon Dioxide (SiO2)

Sandstone (with Iron Staining)

Clastic sedimentary rock (primarily SiO2 with Fe2O3 oxides)

Pebble

Clast (specifically a granule or small pebble)

Green Apophyllite and Stilbite on Quartz Cluster

Apophyllite-(K) (KCa4(Si8O20)(F,OH)·8H2O), Stilbite-Ca (NaCa4(Si27Al9)O72·28H2O), Quartz (SiO2)

Sandstone

Arenite (primarily SiO2)

Granite

Granite (Mainly Quartz: SiO2, Feldspar: KAlSi3O8 – NaAlSi3O8 – CaAl2Si2O8, and Mica)