Microcrystalline Quartz

Red jasper (likely iron-rich chert)

Microcrystalline quartz, SiO₂, colored by hematite/goethite

Tumbled brown jasper (likely iron-rich chert)

Microcrystalline quartz, SiO₂, with iron-oxide impurities

River Pebbles (Chert and Quartzite)

Sedimentary Clastic Rock (Silica-rich)

Yellow Jasper

Silicon Dioxide (SiO2) with iron inclusions

Red/orange chalcedony (carnelian), possibly dyed or heat-treated

Chalcedony, cryptocrystalline SiO₂ (quartz variety)

Agate

Silicon Dioxide / Cryptocrystalline Quartz (SiO2)

Black Chert (Flint / Basanite)

Microcrystalline / Cryptocrystalline Quartz (SiO2)

Red jasper

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

Tumbled orange chalcedony (likely carnelian)

Chalcedony, microcrystalline quartz (SiO₂), orange variety commonly called carnelian

Red Jasper

Silicon Dioxide (Quartz variety), SiO2

Picture Jasper

Silicon Dioxide (SiO2) with iron oxide and clay impurities

Petrified Wood

Silicified Wood (SiO2)

Iron-rich jasper (possibly brecciated jasper)

Jasper, microcrystalline quartz (SiO₂) colored by iron oxides such as hematite and goethite

Jasper and Basalt (Lake Superior Agate or Jasper Pebble)

Silicified rock / Cryptocrystalline quartz (SiO2) with basalt matrix

Blue Dyed Agate

Cryptocrystalline Quartz (SiO2)

Banded Chert or Agate

Silicon Dioxide (SiO2)

Yellow Jasper (with Iron staining)

Silicon Dioxide (SiO2)

Agate

Silicon Dioxide (SiO2) - Chalcedony variety

Polished/tumbled jasper

Jasper, microcrystalline quartz (SiO₂) with iron-oxide and other mineral impurities

Banded chert or jasper pebble

Microcrystalline quartz (SiO₂), likely chert/jasper with iron-oxide staining

Tumbled jasper or chalcedony pebble

Microcrystalline quartz (SiO₂), likely jasper/chalcedony with iron-oxide staining

Tumbled chert or flint pebble

Microcrystalline quartz (SiO₂), likely chert; exact variety uncertain from the image

Tumbled jasper or iron-rich chert fragments

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

Likely polished dark stone (identity uncertain)

Undetermined; possibly polished basalt, chert, or another dark silicate rock

Agate Geode

Silicon Dioxide (SiO2) - Banded Chalcedony

Chert (Flint variety)

Chert (SiO2)

Tumbled orange-and-white jasper or brecciated chalcedony

Microcrystalline quartz (SiO₂), likely iron-oxide-stained jasper; exact variety cannot be confirmed from the image

Tumbled red jasper (likely brecciated jasper)

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

Polished brecciated jasper

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

Tumbled Purple Agate

Silicon Dioxide (SiO2) - Chalcedony variety

Banded Agate (Lake Superior Agate type)

Agate (Cryptocrystalline Variety of Quartz, SiO2)

Polished/tumbled chert or jasper pebble

Microcrystalline quartz (SiO₂), likely brown jasper/chert

Polished yellow-brown jasper

Jasper, a microcrystalline variety of quartz (SiO₂), commonly containing iron-oxide impurities

Jasper with Quartz Druzy

Silicon Dioxide (SiO2)

Tumbled iron-rich chert or jasper

Microcrystalline quartz (SiO₂), likely limonitic/hematitic variety

Jasper

Jasper (SiO2 plus impurities)

Tumbled jasper or chert pebble

Microcrystalline quartz (SiO₂), likely iron-stained jasper/chert

Polished brecciated jasper

Jasper, microcrystalline quartz (SiO₂), with iron-oxide and silica vein infill

Red jasper

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

Tumbled jasper or altered chalcedony

Microcrystalline quartz (SiO₂), possibly jasper/chalcedony

Iron-stained jasper (likely orbicular/brecciated jasper)

Microcrystalline quartz, SiO₂, colored by iron oxides/hydroxides

Tumbled brecciated jasper

Jasper, a microcrystalline quartz variety (SiO₂), with iron-oxide-rich matrix or veining