Mineral (Chalcedony Variety)

Agate Geode

Silicon Dioxide (SiO2)

Botryoidal chalcedony (likely common opal)

Silica, SiO₂; chalcedony is microcrystalline quartz, while opal is hydrated amorphous silica (SiO₂·nH₂O)

Polished brecciated jasper

Jasper, microcrystalline quartz (SiO₂), with iron-oxide inclusions

Red chalcedony (likely carnelian)

Chalcedony, microcrystalline quartz (SiO₂); red color commonly from iron oxides

Tumbled jasper (likely brecciated or red jasper)

Jasper, microcrystalline quartz/chalcedony (SiO₂), colored by iron oxides

Polished jasper pebble

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

Red jasper (likely brecciated jasper/chalcedony)

Microcrystalline quartz, SiO₂, chiefly chalcedony with iron-oxide inclusions

Tumbled orange chalcedony or carnelian

Microcrystalline quartz (SiO₂), likely iron-stained chalcedony/carnelian

Banded Agate

Silicon Dioxide (SiO2)

Grey Agate

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Red jasper

Microcrystalline quartz (SiO₂), iron-oxide-rich chalcedony

Tumbled jasper (likely brecciated or orbicular jasper)

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

Agate Bookend / Quartz Geode

Silicon Dioxide (SiO2)

Jasper

Jasper (Silicon Dioxide, SiO2)

Red Jasper

Silicon Dioxide (SiO2) with Hematite (Fe2O3)

Milky Quartz

Silicon Dioxide (SiO2)

Black Jasper (Etched)

Silicon Dioxide (SiO2) with impurities

Yellow Jasper

Silicon Dioxide with iron inclusions (SiO2)

Red Jasper

Silicon Dioxide (SiO2) with Iron Oxide inclusions

Yellow Jasper

Chalcedony (SiO2) with iron oxide inclusions

Banded Calcite (Mexican Onyx)

Calcite (CaCO3)

Banded Calcite (often sold as Onyx Marble)

Calcium Carbonate (CaCO3)

Banded Agate

Agate (Silicon Dioxide, SiO2)

Carnelian Agate

Chalcedony (Silicon Dioxide, SiO2)

Carnelian (a variety of Chalcedony)

Silicon Dioxide (SiO2) with iron oxide impurities

Carnelian (Chalcedony variety)

SiO2 (Silicon Dioxide)

Chalcedony (Quartz variety)

Silicon Dioxide (SiO2)

Carnelian (a variety of Chalcedony)

Cryptocrystalline Quartz (SiO2) with iron oxide inclusions

Banded agate (polished agate slice)

Agate, a variety of microcrystalline quartz (SiO₂; chalcedony)

Jasper (brecciated or orbicular variety)

Silicon dioxide (SiO2) with iron oxide inclusions

Tumbled Chalcedony

Quartz (Silicon Dioxide - SiO2)

Likely polished agate or chalcedony pebble

Chalcedony, microcrystalline quartz (SiO₂); exact variety cannot be confirmed from the image

Polished agate (likely)

Banded chalcedony, a microcrystalline variety of quartz (SiO₂)

Chert or chalcedony fragment

Microcrystalline quartz (SiO₂), likely ferruginous chalcedony/jasper

Tumbled honey-brown chalcedony or agate

Microcrystalline quartz (SiO₂), likely chalcedony; exact identification requires testing

Ocean Jasper

Spherulitic Chalcedony (SiO2)

Polished brown jasper

Jasper (microcrystalline quartz, SiO₂), likely iron-oxide-rich variety

Jasper Beads (Polished)

Silicon Dioxide (SiO2)

Red Jasper

Jasper (Silicon Dioxide) - SiO2

Tumbled chalcedony (likely yellow/brown agate or carnelian)

Microcrystalline quartz, SiO₂; chalcedony with possible iron-oxide staining

Botryoidal chalcedony (likely quartz with iron staining)

Chalcedony, cryptocrystalline SiO₂; possible quartz druse and limonite/goethite inclusions

Tumbled brown quartz/chalcedony (probable)

Quartz, SiO₂; possibly brown chalcedony or jasper