Sedimentary Rock

Schist

Mica Schist (primarily Muscovite or Biotite sheet silicates)

Laterite

Laterite (no specific mineral formula as it's a rock type)

Gneiss (specifically Biotite Gneiss)

Gneiss (high-grade metamorphic rock primarily composed of Silicates)

Granite

Phaneritic plutonic rock (primarily Quartz, Feldspar, and Mica)

Amethyst

Amethyst (Silicon Dioxide, SiO2)

Carnelian (Red Chalcedony)

Silicon Dioxide (SiO2)

Opal

Hydrated Amorphous Silica (SiO2·nH2O)

African Turquoise (Jasper)

Polychrome African Jasper (often marketed as 'African Turquoise' due to its color, but it is not true turquoise)

Quartz with Iron Stains

Quartz (SiO2) with iron oxide/hydroxide staining

Banded Gneiss

Gneiss (High-grade Regional Metamorphic Rock)

Quartz Druzy on Matrix (likely Agate or Jasper)

Silicon Dioxide (SiO2) with various mineral inclusions

Almandine Garnet

Iron aluminum silicate (Fe3Al2(SiO4)3)

Chert Pebble (Jasper variant)

Microcrystalline Quartz (SiO2)

Graphite-veined Quartzite

Meta-sedimentary Quartzite with Carbonaceous/Graphitic Inclusions (SiO2 + C)

Banded Gneiss (River Cobble)

Gneiss (a high-grade metamorphic rock)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Quartz

Quartz (SiO2)

Slate

Foliated Metamorphic Rock (primarily composed of quartz, illite, and chlorite)

Pink Opal

Hydrated Amorphous Silica (SiO2·nH2O)

Opal

Hydrated Amorphous Silica (SiO2·nH2O)

Rough Emerald

Beryl (Be3Al2Si6O18 with Chromium/Vanadium impurities)

Limonite/Goethite on Shale

Hydrous ferric oxides (FeO(OH)·nH2O) often associated with argillaceous rock

Turquoise

CuAl6(PO4)4(OH)8·4H2O (Hydrated copper and aluminum phosphate)

Gneiss (specifically a granitic gneiss cobble)

Gneiss (high-grade regional metamorphic rock)

River Pebble (likely Quartzite or Chert)

Silicon Dioxide (SiO2)

Druzy Quartz (on Geode Fragment)

Silicon Dioxide (SiO2)

Gneiss

Gneiss (High-grade regional metamorphic rock)

Zebra Rock / Zebra Marble

Banded Limestone-Marble Transition

Quartz (Rock Crystal)

Quartz (SiO₂ - Silicon Dioxide)

Basalt

Extrusive mafic igneous rock

Quartz (likely Jasper or Chert variety)

Quartz (SiO₂)

Jasper River Pebble

Silicon Dioxide (SiO2)

Quartz Vein in Host Rock

Silicon Dioxide (SiO2) within metamorphic/igneous matrix

Gossan with Copper Carbonate (Chrysocolla/Malachite)

Ferruginous Oxide (Gossan) with Cu2CO3(OH)2 (Malachite) or (Cu,Al)2H2Si2O5(OH)4 (Chrysocolla)

Precious Opal in Matrix

Hydrated Silica (SiO2·nH2O)

Native Copper within Host Rock

Native Copper (Cu)

Terrazzo (with Marble and Granite fragments)

Cementitious or resinous composite containing Calcium Carbonate (CaCO3) and Silicates

Banded Iron Formation (BIF) with Quartz

Banded Iron Formation, often composed of alternating layers of hematite (Fe2O3) or magnetite (Fe3O4) and chert (microcrystalline quartz, SiO2)

Quartz (various varieties)

SiO₂ (Silicon Dioxide)

Quartz

Quartz (SiO2 - Silicon Dioxide)

Rough Garnet in Matrix

Almandine Garnet (Fe3Al2Si3O12)