Sedimentary (Secondary Classification: Cryptocrystalline Quartz)

Chert Pebble with Quartz Veins

Microcrystalline Quartz (SiO2)

Chalcedony (Yellow Agate)

Cryptocrystalline Quartz (SiO2)

Jasper with Quartz Veining

Silicon Dioxide (SiO2) - Opaque cryptocrystalline variety of Quartz

Red-and-white porphyritic granite fragment

Granite, likely alkali-feldspar granite; quartz + feldspar with minor mafic minerals

Brecciated Jasper

Silicon Dioxide (SiO2) with Hematite and Epidote/Chlorite inclusions

Rounded granitic gneiss or granitoid boulder

Biotite-bearing orthogneiss; chiefly quartz, feldspar, and biotite

Iron-rich breccia or weathered limonite-bearing rock

Goethite–limonite ironstone, possibly ferruginous breccia

Yellow Agate (Banded Chalcedony)

Silicon Dioxide (SiO2)

Red Jasper (with Quartz inclusions)

Silicon Dioxide (SiO2)

Turquoise

Hydrated phosphate of copper and aluminium [CuAl6(PO4)4(OH)8·4H2O]

Dalmatian jasper (often sold as Dalmatian stone)

Porphyritic alkali feldspar–quartz syenite, commonly with black arfvedsonite/aegirine-group amphibole inclusions

Chert (Iron-stained)

Microcrystalline Quartz (SiO2)

Agate Geode

Silicon Dioxide (SiO2)

Blue Chalcedony

Silicon Dioxide (SiO2)

Turquoise

Turquoise - CuAl6(PO4)4(OH)8·4H2O

Chert with Quartz/Calcite Vein

Microcrystalline Silica (SiO2)

Quartz-rich granitoid (likely granite or granodiorite)

Granite–granodiorite; chiefly quartz, feldspar, and minor dark minerals

Chert (Common Opal/Chalcedony mixture)

Silicon Dioxide (SiO2)

Chert (specifically a Worked Flint/Knapped Flake)

Chert / Flint (Microcrystalline Quartz, SiO2)

Agate

Silicon dioxide (SiO2) - variety Chalcedony

Quartz-rich feldspathic rock, possibly weathered granite or quartzite

Likely quartz and feldspar aggregate; exact identification is uncertain from the photograph

Mixed tumbled stones

Mixed mineral specimens; visible pieces may include quartz, feldspar, calcite, and other silicates

Banded Agate (River Stone)

Agate (Silicon Dioxide - SiO2)

Tumbled Jasper

Silicon dioxide with impurities (Microcrystalline Quartz, SiO2)

Pink Dyed Agate (Pink Agate Slice)

Silicon Dioxide (SiO2) - Chalcedony / Cryptocrystalline Quartz

Dalmatian jasper

Dalmatian stone, typically a leucocratic alkali-feldspar-rich porphyritic igneous rock with black arfvedsonite or aegirine inclusions

Vesicular basalt (scoriaceous volcanic rock)

Basalt, chiefly plagioclase, pyroxene, and commonly olivine; vesicles may be lined with secondary minerals

Limonite-stained Chert

Microcrystalline Quartz (SiO2) with Hydrated Iron Oxides (FeO(OH)·nH2O)

Turquoise

Hydrated phosphate of copper and aluminium [CuAl6(PO4)4(OH)8·4H2O]

Red Jasper

Silicon Dioxide (SiO2) with Hematite inclusions

Granite-like granitoid

Felsic intrusive igneous rock, chiefly quartz, feldspar, and minor mica (compositionally near granite or granodiorite)

Tumbled Agate

Silicon Dioxide (SiO2)

Banded Agate (Tumbled)

Silicon Dioxide (SiO2)

Anthracite coal

Anthracite; predominantly carbon (C), with minor mineral impurities

Yellow-green serpentine (likely)

Serpentine-group phyllosilicate, commonly lizardite or antigorite; approximate formula Mg₃Si₂O₅(OH)₄

Dalmatian jasper

Spotted rhyolite (commercially called Dalmatian jasper), chiefly quartz and feldspar with black aegirine/arfvedsonite inclusions

Dyed Blue Agate

Cryptocrystalline Quartz (SiO2)

Ammonite fossil

Fossilized ammonoid cephalopod; likely an involute ammonite, exact genus/species indeterminate

Brown Agate

Cryptocrystalline Silica (SiO2)

Yellow Quartzite (or Yellow Chalcedony Pebble)

Silicon Dioxide (SiO2)

Turquoise

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

Weathered quartz-rich rock, possibly granite or quartzite

Indeterminate; likely quartz (SiO₂) with feldspar and minor dark minerals