Sedimentary (Volcanic)

Amethyst druzy geode

Quartz, SiO₂, purple variety (amethyst)

Agate

Silicon Dioxide (Chalcedony), SiO2

Yellow Agate (Banded Chalcedony)

Silicon Dioxide (SiO2)

Quartz Druzy on Matrix

Silicon Dioxide (SiO2)

Chalcedony (Botryoidal Agate)

Silicon Dioxide (SiO2)

Chalcedony / Agate

Silicon Dioxide (SiO2)

Jasper

Microcrystalline Quartz (SiO2)

Agate

Silicon Dioxide (Chalcedony), SiO2

Red Jasper with Chalcedony Banding

Microcrystalline Quartz (SiO2) with Hematite inclusions

Chert (Common Opal/Jasper variety)

Silicon Dioxide (SiO2)

Likely river-worn dark stone (possibly basalt or shale)

Indeterminate; likely fine-grained basalt (plagioclase–pyroxene), though slate/shale is also possible

Mixed collection of common river stones

Varied lithologies, visibly including quartz-rich rock, dark mafic rock, sandstone, and purple quartz-bearing material

Vesicular Basalt with Epidote/Amygdaloidal Basalt

Amygdaloidal Basalt (Mg, Fe)2SiO4 + Ca2(Al, Fe)3(SiO4)3(OH)

Jasper

Silicon dioxide (SiO2)

Red jasper (likely iron-rich chert)

Microcrystalline quartz (SiO₂), colored by hematite/goethite inclusions

Jasper

Silicon Dioxide (Microcrystalline Quartz, $SiO_2$)

Blue chalcedony or common opal

Cryptocrystalline silica, SiO₂; likely pale blue chalcedony, possibly opal-A

Red jasper (likely)

Jasper, microcrystalline quartz (SiO₂) colored mainly by iron oxides

Tumbled jasper

Microcrystalline quartz (SiO₂), commonly with iron-oxide impurities

Polished orbicular jasper (likely leopard-skin or brecciated jasper)

Microcrystalline quartz (SiO₂) with iron-oxide minerals; exact variety uncertain from the image

Polished red jasper

Jasper, an opaque microcrystalline variety of quartz (SiO₂), colored mainly by iron oxides

Tumbled jasper (likely brecciated or polychrome jasper)

Microcrystalline quartz/chalcedony, SiO₂, with iron-oxide impurities

Red jasper (likely polished or dyed)

Jasper, microcrystalline quartz (SiO₂), commonly colored by iron oxides

Tumbled blue chalcedony (likely dyed)

Cryptocrystalline quartz, SiO₂; chalcedony variety

Tumbled brown jasper (likely brecciated jasper)

Microcrystalline quartz/chalcedony, SiO₂, with iron-oxide and other mineral inclusions

Weathered agate or chalcedony nodule

Microcrystalline quartz (SiO₂), likely chalcedony/agate

Druzy Quartz Geode (with Chalcedony)

Silicon Dioxide (SiO2)

Carnelian Agate

Silicon Dioxide (SiO2) with iron oxide inclusions

Carnelian Agate

Silicon Dioxide (SiO2) - variety of Chalcedony

Botryoidal Chalcedony (Agate)

Silicon Dioxide (SiO2)

Quartz Geode

Silicon Dioxide (SiO2) within Sedimentary or Igneous host

Chalcedony (including Carnelian and Agate variants)

Silicon Dioxide (SiO2)

Carnelian Agate

Silicon dioxide (SiO2) with iron oxide impurities

Poppy Jasper

Microcrystalline Quartz (SiO2) with hematite and other inclusions

Chalcedony

Silicon Dioxide (SiO2)

Pyrite with Vesicular Matrix

Iron Disulfide (FeS2)

Quartz Geode

Silicon Dioxide (SiO2)

Agate (Carnelian Agate with Quartz Matrix)

Silicon Dioxide (SiO2)

Chalcedony (Yellow Agate / Carnelian Chalcedony)

Silicon Dioxide (SiO2)

Banded Agate

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Red Jasper (Chert)

Silicon dioxide with iron inclusions (SiO2)

Carnelian

Red Chalcedony (SiO2)