Not A Rock (Man Made Origin)

Sandstone or Limestone

Arenite or Calcareous Sedimentary Rock

Glacial Cobble (likely Granitic or Gneissic)

Granite/Gneiss Glacial Erratic

Schist

Mica Schist (Medium-grade Metamorphic Rock)

Quartz (Milky/Crystalline)

Silicon Dioxide (SiO2)

Quartz Geode

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

White Topaz

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

Crushed Stone (Basalt/Gabbro)

Mafic Igneous Rock (primarily Plagioclase and Pyroxene)

Limestone (specifically Travertine or Tufa)

Calcium Carbonate (CaCO3)

Metaconglomerate

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

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)

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

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)

Tiger's Iron

Pseudomorphic Quartz Aggregate (contains SiO2 with Fe2O3 and FeOOH)

Sandstone (likely Quartzose Sandstone)

Arenite (SiO2 based)

Banded Gneiss (River Rock/Pebble)

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

Sandstone or Limestone

Sedimentary Rock

Chert (Iron-Stained)

Microcrystalline Silica (SiO2)

Quartz (Milky Quartz vein fragment)

Silicon Dioxide (SiO2)

Basalt

Mafic volcanic rock (primarily plagioclase feldspar and pyroxene)

Quartz on Matrix

Silicon Dioxide (SiO2)

Smoky Quartz

Silicon Dioxide (SiO2)

Sandstone (with Iron Staining)

Clastic sedimentary rock (primarily SiO2 with Fe2O3 oxides)

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)

Banded Sandstone

Arenite (with iron oxide banding)

Sandstone (Wonderstone)

Arenite (composed primarily of SiO2 with Fe2O3 impurities)

Sandstone (Banded Sandstone)

Clastic Sedimentary Rock (primarily SiO2 with iron oxide impurities)

Granite

Granite (Phaneritic Igneous Rock)