Mineral, Often A Rock Given Its Aggregate Nature

Rough Corundum (likely Sapphire/Zircon-bearing)

Aluminium Oxide (Al2O3)

Assorted Decorative Tumbled Stones (Quartz, Sodalite, Aventurine, Calcite)

Mixed Silicates and Carbonates (SiO2, Na8(Al6Si6O24)Cl2, CaCO3)

Granite

Phaneritic Igneous Rock (composed primarily of Quartz, Alkali Feldspar, and Plagioclase)

Yellow Quartzite (River Pebble)

Quartzite (primarily SiO2)

Red Scoria (Lava Rock)

Scoria (Vesicular Basalt/Andesite)

Olivine in Basalt (Peridot)

Magnesium Iron Silicate (Mg,Fe)2SiO4 (Mineral) within Basalt (Rock)

Coquina

Coquina (a type of limestone)

Red Sandstone

Arenite (Ferruginous Sandstone)

Quartz (Drusy/Crystalline variety)

Silicon Dioxide (SiO2)

Quartz Druze on Matrix

Silicon Dioxide (SiO2)

Basalt with Vesicular Texture (Beach Cobble)

Vesicular Basalt (Aphanitic Igneous Rock)

Granite

Granite (Felsic Plutonic Rock)

Red Jasper (Opaque Chalcedony)

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

Sandstone (Red)

Arenite (primarily Quartz, SiO2, with Iron Oxide cement)

Eye Agate (Sulemani Agate)

Banded Chalcedony (SiO2)

Quartzite

Quartzite (SiO2)

Basalt River Rock

Basalt (Aphanitic Mafic Igneous Rock)

Manganese-coated Sandstone

Clastic sedimentary rock with Manganese Oxide (often Pyrolusite or Psilomelane)

Septarian Nodule

Septarian Concretion (CaCO3 with Siderite/Limonite streaks)

Chert (often called Flint when dark)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Basalt River Cobble

Basalt (Mafic Igneous Rock)

Red Jasper

Silicon Dioxide (SiO2) with iron oxide inclusions

Sodalite

Sodalite (Na8(Al6Si6O24)Cl2)

Sandstone

Sandstone (clastic sedimentary rock), primarily SiO2

Carnelian (Agate)

SiO2 (Silicon Dioxide with Iron Oxide impurities)

Quartz (Milky/Common)

Silicon Dioxide (SiO2)

Rose Quartz

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

Pink Opal

Amorphous Hydrous Silica (SiO2·nH2O)

Basalt with Vesicles

Aphanitic Mafic Volcanic Rock (Basalt)

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2)

Granite

Granite (Phaneritic intrusive igneous rock)

Chert / Flint

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Quartz Vein in Host Rock (Gneiss/Schist)

Silicon Dioxide (SiO2) within a metamorphic matrix

Quartz (Smoky/Grey Quartz Variant)

Silicon Dioxide (SiO2)

Granite

Granite (a felsic intrusive igneous rock)

Sandstone (Banded)

Clastic Sedimentary Rock (primarily Quartz, SiO2)

Sandstone (with Iron Staining)

Arenite (composed primarily of SiO2 with Fe2O3 staining)

Bauxite Ore

Hydrated aluminum oxides (e.g., Gibbsite Al(OH)3, Boehmite ̲̲̲̲AlOOH, Diaspore ̲̲̲̲AlOOH)

Milky Quartz (Water-worn Pebble)

Silicon Dioxide (SiO2)

Amethyst

Amethyst (Silicon Dioxide, SiO2)

Amethyst Quartz

Silicon Dioxide (SiO2 with iron impurities)

Fancy Jasper (Multicolor Agate/Jasper)

Silicon Dioxide (SiO2) - Microcrystalline Quartz