Synthetic Glass (Man Made)

Obsidian (in jewelry setting)

Volcanic Glass (Amorphous Silica)

Obsidian

Volcanic glass (SiO2 + impurities)

Quartz Pebble

Silicon Dioxide (SiO2)

Quartz Pebble

Quartz (Silicon Dioxide, SiO2)

Sandstone (with biological crust)

Arenite (SiO2 based)

Quartz (Clear Quartz/Rock Crystal)

Silicon Dioxide (SiO2)

Milky Quartz with Iron Inclusions

Silicon Dioxide (SiO2)

Sandstone (Ferruginous)

Arenite (Fe2O3 enriched)

Sandstone (Quartzose Sandstone)

Clastic Sedimentary Rock - Arenite

Rough Quartz (likely Rose or Smoky variant)

Silicon Dioxide (SiO2)

Quartzite pebble

Quartzite (SiO2)

Clear Quartz

Silicon Dioxide (SiO2)

Quartz (River Pebble)

Silicon Dioxide (SiO2)

Milky Quartz Pebble

Quartz (Silicon Dioxide, SiO2)

Sandstone (Quartzose)

Arenite (primarily SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Quartz Vein / Milky Quartz

Silicon Dioxide (SiO2)

Sandstone (with Iron Staining)

Clastic sedimentary rock (primarily SiO2 with Fe2O3 staining)

Quartzite Pebble

Quartzite (mostly SiO2)

Quartz (Milky/Gray variety)

Silicon Dioxide (SiO2)

Quartz Crystal Point

Silicon Dioxide (SiO2)

Clear Quartz

Silicon dioxide (SiO2)

Sandstone (Calcareous Sandstone)

Calcareous Sandstone (primarily SiO2 with CaCO3 cement)

Quartz (with iron oxide staining)

Silicon Dioxide (SiO2)

Pink Feldspar

Orthoclase Feldspar (KAlSi3O8)

Quartzite Pebble

Metamorphosed Quartz Sandstone (SiO2)

Quartz

Silicon Dioxide (SiO2)

Sandstone (likely Arkose or Quartz Sandstone)

Clastic sedimentary rock (primarily SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Cloudy Quartz

Silicon Dioxide (SiO2)

Quartzite

Quartzite (predominantly SiO2)

Chert (varietal Flint)

Chert (SiO2)

Milky Quartz Pebble

Silicon Dioxide (SiO2)

Chert (specifically Red Chert or Jasper)

Microcrystalline Quartz (SiO2)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Quartz Pebble (Chalcedony/Agate)

Silicon Dioxide (SiO2)

Obsidian

Volcanic Glass (70-75% SiO2)

Pumice

Pumice (Vesicular Felsic Glass)

Obsidian

Volcanic Glass (SiO2 dominant)

Milky Quartz

Silicon Dioxide (SiO2)

Mahogany Obsidian

Volcanic Glass with Hematite inclusions (SiO2 + Fe2O3)

Milky Quartz

Silicon Dioxide (SiO2)