Mineral (Chalcedony)

Dyed Agate / Quartz

Silicon Dioxide (SiO2) with artificial dye

Brown chalcedony (likely carnelian)

Chalcedony, microcrystalline quartz (SiO₂); iron-stained brown variety

Blue lace agate (likely dyed or color-enhanced)

Microcrystalline quartz (chalcedony), SiO₂

Banded Agate

Silicon Dioxide (SiO2) - Chalcedony

Tumbled gray chalcedony (likely agate or quartzite)

Microcrystalline quartz, SiO₂ (chalcedony)

Tumbled brown-and-white banded agate

Chalcedony, microcrystalline quartz (SiO₂)

Moss Agate

Chalcedony (SiO2) with inclusions of manganese or iron oxides

Weathered quartz-rich mineral nodule

Likely quartz (SiO₂) with iron-oxide staining and possibly feldspar/mica; exact identification requires testing

Blue Lace Agate

Chalcedony (a form of Quartz) - SiO2

Polished orbicular jasper (likely ocean jasper)

Silica-rich chalcedony/quartz aggregate with microcrystalline quartz, commonly containing feldspar and iron-oxide inclusions

Chert / Chalcedony

Silicon Dioxide (SiO2)

Polished agate slab (likely moss or plume agate)

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

Tumbled carnelian (likely)

Orange-red chalcedony, microcrystalline quartz (SiO₂)

Dendritic Agate

Silicon Dioxide (SiO2) with Manganese/Iron inclusions

Sardonyx Agate Sphere

Cryptocrystalline Quartz (SiO2) with iron oxide inclusions

Quartz Geode

Silicon Dioxide (SiO2)

Polished banded agate

Agate, a banded variety of chalcedony (microcrystalline SiO₂)

Water-worn chalcedony pebble

Chalcedony, microcrystalline SiO₂; possibly iron-stained agate

Dyed Agate

Chalcedony (Silicon Dioxide, SiO2)

Lake Superior Agate

Silicon Dioxide (Chalcedony variety)

Agate

Silicon Dioxide (Chalcedony), SiO2

Agate

Silicon dioxide (Chalcedony), SiO2

Agate

Silicon Dioxide (Chalcedony), SiO2

Agate

Silicon Dioxide (Chalcedony), SiO2

Tumbled brown agate (possible carnelian or chalcedony)

Microcrystalline quartz, SiO₂; agate is banded chalcedony

Rounded quartz-rich pebble

Microcrystalline quartz (SiO₂), possibly chalcedony or milky quartz

Black onyx-style bead bracelet

Likely polished black chalcedony (microcrystalline quartz, SiO₂); the beads may also be dyed agate or another black stone.

Agate

SiO2

Agate

Cryptocrystalline Silicon Dioxide (SiO2)

Brown chalcedony (agate-like flint/chert fragment)

Chalcedony, microcrystalline quartz (SiO₂); identification is tentative from the photo

Dendritic Agate / Chalcedony

Silicon Dioxide (SiO2) with Manganese/Iron oxide inclusions

Polished blue-gray agate/geode slice (tentative)

Microcrystalline quartz (chalcedony), SiO₂, possibly with druzy quartz

Banded agate geode fragment

Microcrystalline quartz (chalcedony), SiO₂

Agate

Silicon dioxide (Chalcedony), SiO2

Agate

Silicon Dioxide (Chalcedony), SiO2

Chalcedony (Tumbled Agate/Jasper)

Silicon dioxide (SiO2)

Green Jasper / Chalcedony

Silicon Dioxide (SiO2)

Tumbled carnelian

Carnelian, orange-red chalcedony (microcrystalline SiO₂)

Blue-gray chalcedony (likely agate/jasper fragment)

Microcrystalline quartz, SiO₂ (chalcedony)

Chrysocolla in Chalcedony (Gem Silica)

Hydrated copper phyllosilicate and silicon dioxide (SiO2 with (Cu,Al)2H2Si2O5(OH)4)

Chrysocolla

Chrysocolla; (Cu,Al)2H2Si2O5(OH)4·nH2O

Jasper

Silicon dioxide (SiO2)