Industrial Byproduct (Anthropogenic Rock Like Material)

Clear Quartz (Rock Crystal)

Quartz (Silicon Dioxide, SiO2)

Yellow Quartz (Citrine/Quartzite Pebble)

Silicon Dioxide (SiO2)

Quartz (specifically Milky or Clear Chunk)

Silicon Dioxide (SiO2)

Chlorastrolite (Greenstone)

Chlorastrolite (variety of Pumpellyite) - Ca2(Mg,Fe)Al2(SiO4)(Si2O7)(OH)2 · H2O

Red Quartzite River Pebble

Quartzite (SiO2 with iron oxide inclusions)

Sandstone (Pebble/Cobble)

Sandstone (arenite is a more precise term for sandstone with less than 15% matrix; this specimen appears to be a lithic or quartz arenite)

Sandstone (Ferruginous)

Arenite (primarily SiO2 with iron oxide cement)

River Quartz Pitting/Cobble

Silicon Dioxide (SiO2)

Opalite

Man-made glass (traditionally simulated Opal)

Red Sandstone

Arenite (Ferruginous Sandstone)

Chert (Iron-rich or Jasperoid)

Cryptocrystalline Quartz (SiO2)

Sandstone (Ferruginous)

Ferruginous Sandstone (SiO2 with Fe2O3)

Tufa

Calcareous Tufa (CaCO3)

Diorite (Spotted or Dalmatian Stone pattern)

Diorite

Greenstone (Greenschist)

Greenschist facies rock (containing chlorite, actinolite, and epidote)

Red Sandstone

Clastic Terrigenous Sedimentary Rock (primarily SiO2 with Fe2O3 coating)

Sandstone

Sandstone (lithified arenite/wacke)

Sandstone

Arenite (primarily SiO2)

Pink Granite

Granite (Felsic intrusive igneous rock)

Milky Quartz (Water-worn Pebble)

Silicon Dioxide (SiO2)

Sulfur (in host rock)

Native Sulfur (S8)

Petrified Wood

Silicified Wood (primarily SiO2 - Silicon Dioxide / Chalcedony)

Sandstone

Sandstone (clastic sedimentary rock, composed predominantly of sand-sized minerals or rock fragments)

Pumice

Pumice (a highly vesicular extrusive volcanic rock)

Agate (Thunderegg segment)

Silicon dioxide (SiO2) - Microcrystalline Quartz/Chalcedony

Mica Schist with Pyrite

Muscovite/Biotite Schist with Iron Sulfide (FeS2)

Chert (Jasper variety)

Silicon Dioxide (SiO2)

Chert / Flint Nodule

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Moissanite

Silicon Carbide (SiC)

Chert (also known as Flint or Common Chalcedony)

Cryptocrystalline Silica (SiO2)

Chert (variously identified as Flint)

Microcrystalline Quartz (SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Chert (Jasper/Flint variety)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Sandstone

Arenite (primarily SiO2)

Chert (specifically Zebra Chert/Flint)

Silicon Dioxide (SiO2)

Chert (Brecciated or Veined)

Silicon Dioxide (SiO2)

Sandstone (Graywacke type)

Clastic Sedimentary Rock (Lithic Sandstone)

Slate

Slate (Low-grade foliated metamorphic rock)

Dendritic Agate (or Dendritic Opal)

SiO2 (for Agate), SiO2·nH2O (for Opal)

Granitic Pegmatite

Coarse-grained Granite (KAlSi3O8 + SiO2)

Diamond (Cut Gemstone)

Carbon (C)

Green Slate (Greenstone)

Foliated Metamorphic Rock (rich in Chlorite/Epidote)