Organic Structure (Not A Rock)

Petrified Wood

Silicified Wood (SiO2)

Schist (Biotite Schist)

Biotite-bearing Schist (K(Mg,Fe)3AlSi3O10(F,OH)2)

Granite with Mafic Inclusions

Granite (Phaneritic igneous rock composed of Quartz, Feldspar, and Mica)

Mica Schist

Mica Schist (primarily Muscovite or Biotite KAl2(AlSi3O10)(OH)2)

Granite

Phaneritic Intrusive Igneous Rock (composed of Quartz, Feldspar, and Mica)

Mica Schist

Mica Schist (predominantly Muscovite or Biotite sheet silicates)

Amethyst

Amethyst (Silicon Dioxide, SiO2)

Porphyritic Basalt (Chinese Writing Stone)

Porphyritic Basalt with Feldspar Phenocrysts

Quartzite with Hematite staining

Quartzite (SiO2) with iron oxide inclusions

Schist

Mica Schist

Gneiss (specifically Banded Gneiss)

Gneiss

Quartzite (River Pebble)

Meta-quartzite (composed primarily of SiO2)

Basalt

Basalt

Sandstone (Fossiliferous)

Clastic Sedimentary Rock (primarily SiO2)

Greenschist (Greenstone)

Chlorite Schist / Greenschist Facies Rock

Chert (Flint Nodules)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (often called Flint or Jasper)

Silicon Dioxide (SiO2)

Agate

Silicon dioxide (SiO2) - variety Chalcedony

Red Jasper (possibly Red Coral or dyed Howlite)

Silicon Dioxide (SiO2) with Iron Oxide inclusions

Fossil Shell in Sedimentary Matrix

Bivalvia (fossil) in Calcium Carbonate Matrix

Gold Ore (in Quartz/Sulfide matrix)

Native Gold (Au) in Quartz (SiO2) and Pyrite (FeS2)

Granite Pebble

Granite (composed primarily of Quartz, Feldspar, and Mica)

Limestone

Calcium Carbonate (CaCO3)

Amethyst

Silicon Dioxide (SiO2) with iron impurities

Hematite Nodules (Moqui Marbles style)

Iron Oxide (Fe2O3)

Hag Stone

Porous sedimentary rock (typically Flint, Chert, or Sandstone) with naturally occurring holes

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2 with iron oxide inclusions)

Sandstone

Arenite (SiO2 primarily)

White Marble

Recrystallized Calcite (CaCO3) / Marble

Sandstone

Arenite (primarily SiO2)

Clear Quartz

SiO2 (Silicon Dioxide)

Slag (Industrial Byproduct)

Artificial silicate/iron byproduct

Sandstone

Clastic sedimentary rock (primarily SiO2)

Mixed Quartz and River Pebbles (Stone Collection)

Mixed assortment containing mainly Silicon Dioxide (SiO2)

Sandstone

Arenite (composed primarily of SiO2)

Sandstone

Arenite (SiO2 primarily)

Sandstone (Greywacke/Siltstone variant)

Arenite / Wacke (SiO2 with diverse mineral inclusions)

Amethyst

Silicon Dioxide (SiO2) with iron impurities

Lapis Lazuli (polished cabochon/sphere)

Na8[Al6Si6O24]Sn with accessory minerals (Pyrite, Calcite)

Chert (Agatized)

Silicon dioxide (SiO2)

Asphalt Concrete

Bituminous conglomerate

Sandstone

Arenite (SiO2 based)