Organic Structure (Not A Rock)

Epidote

Epidote Group (Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH))

Sandstone Concretion

Septarian or Carbonate-cemented Sandstone Concretion

Chert (specifically Jasper)

Silicon dioxide (SiO2) with iron oxide inclusions

Milky Quartz

Crystalline Silicon Dioxide (SiO2)

Milky Quartz Pebble

Quartz (Silicon Dioxide, SiO2)

Copper Ore (with Malachite and Azurite)

Hydroxide copper carbonate (Cu2CO3(OH)2 / Cu3(CO3)2(OH)2)

Amethyst

Silicon Dioxide with Iron impurities (SiO2 + Fe3+)

Quartzite

Quartzite (SiO2)

Sandstone (Greywacke/Siltstone variant)

Clastic Sedimentary Rock (composed primarily of Quartz SiO2 and Feldspar)

Jasper

Silicon dioxide / Chalcedony (SiO2)

Rose Quartz

Silicon Dioxide (SiO2) with trace amounts of Titanium, Iron, or Manganese

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2 with inclusions of Iron Oxide)

Red Jasper

Silicon Dioxide (SiO2) with Iron Oxide (Fe2O3) inclusions

Sandstone (with prominent jointing/fractures)

Arenite (composed primarily of SiO2)

Clear Quartz

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Sandstone (Ferruginous)

Arenite (with Iron Oxide)

Quartz Druzy Geode

Silicon Dioxide (SiO2)

Limestone

Calcium Carbonate (CaCO3)

Greenstone / Serpentinite

Serpentinite (composed largely of Serpentine group minerals, Mg3Si2O5(OH)4)

Limestone

Calcium Carbonate (CaCO3)

Chalcedony (Agate/Quartz)

Silicon Dioxide (SiO2)

Picture Jasper

Silicon Dioxide (SiO2)

Coral Fossil (Favosites type)

Phylum Cnidaria, Class Anthozoa (often CaCO3 - Calcium Carbonate)

Amygdaloidal Basalt

Amygdaloidal Basalt (Mafic volcanic rock including secondary mineral infills)

Sandstone (Banded)

Clastic sedimentary rock (primarily SiO2)

Sandstone (Ferruginous)

Arenite (primarily SiO2 with Fe2O3 staining)

Carnelian Agate

Silicon Dioxide (SiO2) - variety of Chalcedony

Pink Granite / Gneiss

Felsic Plutonic Rock (Granite) with Gneissic banding

Milky Quartz (among River Rock)

Quartz (Silicon Dioxide, SiO2)

Rose Quartz

Silicon Dioxide (SiO2) with trace amounts of titanium, iron, or manganese

Tiger's Eye

SiO2 (Silicon Dioxide with inclusions of Goethite/Limonite)

Milky Quartz with Iron Inclusions

Silicon Dioxide (SiO2)

Granitic Pegmatite

Pegmatitic Granite

Sandstone (likely River-tumbled Picture Sandstone)

Arenite (predominantly SiO2 with iron oxide impurities)

Quartz with Limonite Staining

Silicon Dioxide (SiO2) with Hydrated Iron Oxide (FeO(OH)·nH2O)

Basalt

Basalt (containing Pyroxene, Plagioclase Feldspar, and Olivine)

Ferruginous Quartz

Quartz (Silicon Dioxide) with Iron Inclusion, SiO2

Sandstone (Quartzite-rich)

Clastic sedimentary rock (SiO2 primary)

Sandstone (likely Arkose)

Arenite (composed mainly of SiO2 with Feldspar)

Serpentinite

Serpentinite (Mg, Fe, Ni, Al, Zn, Mn)2-3(Si, Al, Fe)2O5(OH)4

Pink Granite

Phaneritic Felsic Igneous Rock (composed of orthoclase, quartz, and plagioclase)