Obsidian
Volcanic Glass (predominantly SiO2)
Category
Browse mixed (predominantly sedimentary and igneous) specimens identified by the Rock Identifier community.
Obsidian
Volcanic Glass (predominantly SiO2)
Obsidian
Volcanic Glass (predominantly SiO2)
Obsidian (specifically Rainbow or Silver Sheen Obsidian)
Volcanic Glass (predominantly SiO2)
Black Obsidian
Volcanic Glass (predominantly SiO2)
Obsidian
Volcanic Glass (predominantly SiO2)
Amazonite
Microcline (KAlSi3O8)
Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
Blue Lace Agate
Cryptocrystalline Quartz (SiO2)
Black Tourmaline (Schorl)
Schorl (Na(Fe²⁺)₃Al₆(BO₃)₃Si₆O₁₈(OH)₄)
Pyrope Garnet
Magnesium aluminum silicate (Mg3Al2Si3O12)
Amazonite
Potassium Feldspar (KAlSi3O8)
Petoskey Stone
Hexagonaria percarinata (Fossilized Rugose Coral)
Quartz (Crystal Cluster)
Silicon Dioxide (SiO2)
Citrine
Silicon Dioxide (SiO2) with iron impurities
Chrysocolla Chalcedony
Hydrated Copper Phyllosilicate (Cu,Al)2H2Si2O5(OH)4 + SiO2
Milk Quartz (White) and Yellow Aventurine (Yellow)
Silicon Dioxide (SiO2)
Blue Lace Agate
Chalcedony (SiO2) with trace impurities
Blue Lace Agate
Silicon Dioxide (SiO2) - Variety of Chalcedony
Rose Quartz
Silicon Dioxide (SiO2)
Citrine
Silicon Dioxide (SiO2) with iron impurities
Fuchsite
K(Al,Cr)2(AlSi3O10)(OH)2 (Chromium-rich Muscovite)
Epidotite (Unakite variety)
Epidotized Granite (Ca2(Al2,Fe)(SiO4)(Si2O7)O(OH))
Ironstone Concretion (Moqui Marble)
Iron Oxide Concretion (Goethite and Hematite around a Sandstone core)
Carnelian (Chalcedony)
Silicon Dioxide (SiO2)
Obsidian
Volcanic Glass (SiO2)
Obsidian and Phantom Quartz
Volcanic Glass (SiO2 + MgO + Fe3O4) and Crystalline Quartz (SiO2)
Lunar Meteorite (Feldspathic Breccia)
Lunar Achondrite (Regolith Breccia)
Ocean Jasper (Orbicular Jasper)
Orbicular Rhyolite (SiO2)
Yooperlite (Syenite clast containing fluorescent Sodalite)
Sodalite-bearing Syenite
Rose Quartz
Silicon Dioxide (SiO2) with trace amounts of titanium, iron, or manganese
Jasper and Quartzite mix
Silicon Dioxide (SiO2) with impurities
Amethyst
Silicon Dioxide (SiO2) with iron impurities
Citrine
Silicon Dioxide (SiO2) with iron impurities
Chert (often called Flint in dark varieties)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Amethyst (Quartz)
Silicon Dioxide (SiO2)
Labradorite
Labradorite (a calcium-enriched feldspar mineral), (Ca, Na)(Al, Si)4O8
Dalmatian Stone
Dalmatian Stone (a fine-grained igneous rock, often misidentified as Dalmatian Jasper)
Kambaba Jasper
Rhyolite (with Stromatolite fossil inclusions)
Citrine Geode Fragment
Citrine (Silicon Dioxide with Iron Impurities), SiO2
Chert (Flint)
Chert (SiO2)
Chert (specifically Jasper/Flint)
Microcrystalline Quartz (SiO2)
Olivine (in Peridotite/Dunite form)
Magnesium Iron Silicate (Mg,Fe)2SiO4