Sedimentary Rock (Technically A Microcrystalline Quartz Mineral Aggregate)

Quartz Geode

Silicon Dioxide (SiO2) within a geode

Quartz Veined Rock (Likely Graywacke or Quartzite)

Silicon Dioxide (SiO2) veins in Metasedimentary matrix

Tree Agate

Silicon Dioxide (SiO2) - Dendritic Agate/Chalcedony

Quartzite

Quartzite (primarily Silicon Dioxide, SiO2)

Chert (Jasper variety)

Silicon Dioxide (SiO2)

Vesicular Basalt with Epidote

Vesicular Basalt (Mg, Fe)2SiO4 with Epidote (Ca2(Al2,Fe)(SiO4)(Si2O7)O(OH))

Red Chert

Microcrystalline Quartz (SiO2)

Chert / Jasper

Microcrystalline Quartz (SiO2)

Chert (Jasper/Agate variety)

Microcrystalline Quartz (SiO2)

Agate Slices and Clear Quartz Points

Agate (SiO2 Chalcedony) and Clear Quartz (SiO2 Crystalline)

Agate (Polished Nodule)

Agate (Silicon Dioxide, SiO2)

Quartzite (River Pebble)

Quartzite (composed primarily of Silica, SiO2)

Chert (Field Stone)

Microcrystalline Quartz (SiO2)

Chert (Flint)

Microcrystalline Quartz (SiO2)

Yellow Agate

Chalcedony (cryptocrystalline Quartz), SiO2

Chert (Chalcedony/Agate)

Microcrystalline Quartz (SiO2)

Crazy Lace Agate

Silicon Dioxide (SiO2) with iron and aluminum inclusions

Green Jasper

Silicon Dioxide (SiO2) with iron silicate inclusions

Conglomerate

Conglomerate (clastic sedimentary rock)

Quartz Pebble

Silicon Dioxide (SiO2)

Chalcedony in Matrix

Silicon Dioxide (SiO2)

Indian Agate

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Chert (Jasper/Agate variety)

Microcrystalline Quartz (SiO2)

Pickled Dragon Eggs (Fictional Interpretation: Purple Agate or Amethyst Geodes)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Chert (vuggy/nodular)

Microcrystalline Quartz (SiO2)

Shale with Iron Oxide Staining

Fissile Mudstone (primarily clay minerals and quartz)

Black Obsidian

Obsidian (Volcanic Glass)

Gneiss (Granitic Gneiss)

Gneiss (from German Gneis, related to 'spark')

Quartz Vein in Sedimentary Matrix

Silicon Dioxide (SiO2) with host rock

Chert (Jasper/Chalcedony variety)

Microcrystalline Quartz (SiO2)

River Rock / Stream Pebble

Fluvial Clast / Rounded Sedimentary Particle

Chert (Arrowhead Fragment)

Microcrystalline Quartz (SiO2)

Chert (Jasper/Flint variety)

Microcrystalline quartz (SiO2)

Chert Pebble

Microcrystalline Quartz (SiO2)

Chert

Microcrystalline Quartz (SiO2)

Chert (Flint)

Microcrystalline Quartz (SiO2)

Chert (often called Flint or River Stone)

Microcrystalline Quartz (SiO2)

Chert (Iron-stained)

Microcrystalline Quartz (SiO2)

Chert (Flint)

Microcrystalline Quartz (SiO2)

Quartzite River Rock

Quartzite (SiO2)

Crushed Stone (Gravel/Aggregates)

Crushed rock aggregate (varied composition including Granite, Limestone, and Quartz)

Chert (Nodule)

Microcrystalline Quartz (SiO2)