Obsidian

Volcanic Glass (Amorphous Silica)

igneous

Amazonite

KAlSi3O8 (Potassium Aluminum Silicate)

mineral

Rose Quartz

Silicon Dioxide (SiO2)

mineral

Red Jasper

Silicon Dioxide (SiO2) with iron oxide inclusions

sedimentary

Carnelian

Carnelian (Silica, SiO2)

mineral

Clear Quartz

Silicon Dioxide (SiO2)

mineral

Clear Quartz

Silicon Dioxide (SiO2)

mineral

Chakra Stone Tower (Composite Multi-Mineral)

Crystalline Silicon Dioxide composite (SiO2) with various inclusions

mineral

Amethyst (Polished Point)

Crystalline Quartz (SiO2 with iron impurities)

mineral

Citrine

Silicon dioxide (SiO2)

mineral

Chevron Amethyst

SiO2 (Quartz with Manganese/Iron impurities)

mineral

Marble (Sculculpted)

Metamorphosed Limestone (primarily CaCO3)

metamorphic

Opalite

Synthetic Glass (Amorphized Silicon Dioxide)

mineraloid

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2)

mineral

Basalt

Basalt (Mafic volcanic rock)

igneous

Amethyst

SiO2 (Silicon Dioxide)

mineral

Calcite

Calcium Carbonate (CaCO3)

mineral

Petrified Wood

Silicified Wood (SiO2)

sedimentary

Gneiss

Gneiss (High-grade metamorphic rock)

metamorphic

Basalt (Weathered)

Extrusive mafic volcanic rock

igneous

Almandine Garnet

Almandine, Fe3Al2(SiO4)3

mineral

Obsidian

Volcanic glass

igneous

Obsidian

Obsidian (Volcanic Glass)

igneous

Petrified Wood

Silicified Wood (primarily Chalcedony or Quartz, SiO2)

sedimentary

Quartzite with Hematite

Metamorphosed Quartz Sandstone (SiO2 with Fe2O3 inclusions)

metamorphic

Quartz with Hematite Staining

Silicon Dioxide (SiO2) with Ferric Oxide (Fe2O3) inclusions

mineral

Quartz-veined Mudstone or Argillite

SiO2 (Quartz) in Siltstone/Mudstone matrix

sedimentary

Quartzite River Rock

Quartzite (SiO2)

metamorphic

Quartzite

Quartzite (primarily SiO2)

metamorphic

Quartzite

Quartzite (SiO2 silicon dioxide)

metamorphic

Greenstone

Greenschist

metamorphic

Milky Quartz

Quartz (Silicon Dioxide - SiO2)

mineral

Mahogany Obsidian

Volcanic glass containing Magnetite/Hematite

igneous

Chert (Black Flint)

Chert (Microcrystalline Quartz, SiO2)

sedimentary

Amethyst

Silicon Dioxide (SiO2) with trace Iron (Fe3+)

mineral

Agate (Nodule/Chert)

Silicon Dioxide (SiO2)

sedimentary

Botryoidal Agate / Chalcedony Geode

Silicon Dioxide (SiO2)

mineral

Montana Moss Agate

Chalcedony (SiO2) with Manganese/Iron oxide inclusions

sedimentary

Peridot (Olivine)

Magnesium Iron Silicate (Mg, Fe)2SiO4

mineral

Green Fluorite

Calcium Fluoride (CaF2)

mineral

Goldstone

Aventurine Glass (Man-made)

mineral

Blue Dyed Agate

Chalcedony (SiO2) with artificial pigment

mineral