Man Made Material, Not A Natural Rock Or Mineral Specimen

Biotite Schist (likely)

Biotite Schist (rock), Biotite (mineral)

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

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

Sandstone

Clastic sedimentary rock (primarily SiO2)

Druzy Quartz on Agate/Chert

Silicon Dioxide (SiO2)

Granite

Phaneritic plutonic rock (Felsic)

Sandstone (Ferruginous)

Arenite (SiO2 with iron oxide impurities)

Smoky Quartz on Feldspar (Granite Pegmatite)

Silicon Dioxide (SiO2) with Potassium Aluminum Silicate (KAlSi3O8)

Amethyst

Amethyst (Silicon Dioxide with iron impurities, SiO2)

Sandstone (with Iron Oxide staining)

Arenite (primarily SiO2 with Fe2O3 staining)

Basalt (Amygdaloidal)

Amygdaloidal Basalt

Diamond

Native Carbon (C)

Sapphire (likely blue synthetic sapphire or blue glass in a ring)

Corundum (Al₂O₃), specifically the blue variety due to trace amounts of iron and titanium impurities. If synthetic, it would still be Al₂O₃.

Green Aventurine

Quartzite (variety Aventurine) with Fuchsite inclusions (K(Al,Cr)2(AlSi3O10)(OH)2)

Limonite (after Pyrite Pseudomorph)

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

Orange Calcite

Calcium Carbonate (CaCO3)

Veined Quartz

SiO2 (Silicon Dioxide)

Staurolite (Cross Stone)

Staurolite (Fe2+2Al9Si4O23(OH))

Quartz (in matrix)

Quartz (SiO₂)

Chert (Iron-stained)

Microcrystalline Quartz (SiO2)

Smoky Quartz

Silicon Dioxide (SiO2)

Sandstone (with Iron Staining)

Clastic Sedimentary Rock (primarily Quartz, SiO2)

Sandstone

Arenite (Sedimentary rock comprising sand-sized grains)

Basalt River Stone

Basalt (Aphanitic Mafic Igneous Rock)

Blue Sapphire

Corundum (Al2O3)

Sandstone

Arenite

Basalt (River Stone)

Aphanitic Mafic Igneous Rock

Diamond

Carbon (C)

Zirconia (Ceramic) & Ion-X Glass

Zirconium Dioxide (ZrO2) and Ion-strengthened Aluminosilicate Glass

Banded Agate (Dyed Purple)

Agate (Variety of Chalcedony/Quartz), SiO2

Chert (Yellow Jasper/Flint)

Microcrystalline Quartz (SiO2)

Chiastolite (Andalusite)

Al2SiO5

Sandstone

Clastic sedimentary rock (primarily SiO2)

Sandstone

Arenite

Sandstone (Quartzose)

Arenite (primarily SiO2)

Fluorite

Calcium Fluoride (CaF2)

Smoky Quartz

Smoky Quartz (Silicon Dioxide - SiO2)

Milky Quartz (with potential inclusion)

Silicon Dioxide (SiO2)

Blue Topaz (facetted in jewelry)

Aluminum silicate fluoride hydroxide (Al2SiO4(F,OH)2)

Sea Glass (Cobalt Blue)

Amorphous Silica (Glass with Cobalt additives)

Quartz (Druzy) in host rock

SiO₂ (Silicon Dioxide) as Quartz, with unspecified host rock components (likely silicates and iron oxides)

Moonstone

Orthoclase Feldspar (KAlSi3O8)

Petrified Wood

Silicified wood (primarily Silicon Dioxide - SiO2)