Aventurine
Aventurine Quartz (SiO2 with inclusions)
Category
Browse industrial byproduct (often mistaken for obsidian or mineral) specimens identified by the Rock Identifier community.
Aventurine
Aventurine Quartz (SiO2 with inclusions)
Blue Quartzite
Blue Quartzite (Primary mineral: Quartz, SiO2 with magnesio-riebeckite or crocidolite inclusions)
Snowflake Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with Cristobalite inclusions)
Sodalite
Na8(Al6Si6O24)Cl2
Green obsidian (likely molded or heat-treated glass-like specimen)
Volcanic glass; predominantly rhyolitic composition (silica-rich amorphous SiO₂)
Vesicular Basalt with Epidote/Amygdaloidal Basalt
Amygdaloidal Basalt (Mg, Fe)2SiO4 + Ca2(Al, Fe)3(SiO4)3(OH)
Quartz (Iron-stained)
Silicon Dioxide (SiO2)
Quartz (Iron-stained)
Silicon Dioxide (SiO2) with Hematite/Limonite impurities
Ironstone Concretion / Limonite
Goethite and Limonite (FeO(OH)·nH2O)
Obsidian
Obsidian (Volcanic glass, primarily SiO2)
Obsidian
Volcanic Glass (Silica / SiO2)
Sandstone Concretion
Sedimentary Concretion (Quartz sandstone with iron oxide cement)
Obsidian
Volcanic Glass (SiO2)
Obsidian
Volcanic Glass (predominantly SiO2, approximately 70% or more)
Obsidian
Volcanic Glass (Amorphous silicon dioxide with trace impurities)
Mahogany Obsidian
Volcanic glass containing Hematite or Magnetite (SiO2 + Fe2O3)
Blue Apatite
Apatite (Calcium Phosphate) - Ca5(PO4)3(F,Cl,OH)
Limonite Concretion (Goonie or Rattlestone)
Limonite (FeO(OH)·nH2O)
Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with impurities)
Green Quartzite (Tumbled)
Metamorphosed Quartz-rich Sandstone
Ferruginous Sandstone with Concretion
Sandstone (SiO2 dominated with Fe2O3 cement)
Apache Tear
Obsidian (Natural volcanic glass)
Diorite
Phaneritic Intermediate Igneous Rock
Chert Concretion / Nodule
Microcrystalline Quartz (SiO2)
Limestone with Lichen
Calcium Carbonate (CaCO3) with Endolithic/Epilithic Lichen
Sodalite
Sodalite (Na8(Al6Si6O24)Cl2)
Sodalite
Sodalite (Na8Al6Si6O24Cl2)
Mahogany Obsidian
Volcanic Glass with Hematite/Magnetite inclusions (SiO2 + Fe2O3)
Dioptase
Dioptase (CuSiO2(OH)2)
Quartzite Pebble
Metamorphosed Quartz Sandstone (SiO2)
Obsidian
Volcanic Glass (felsic composition)
Obsidian
Volcanic Glass (Amorphous Silicon Dioxide)
Obsidian
Volcanic Glass (Silicon Dioxide with impurities)
Quartzite
Quartzite (SiO2)
Mahogany Obsidian
Volcanic glass containing Magnetite/Hematite
Quartz Pebble (Sea Glass-like Quartz)
Quartz (Silicon Dioxide - SiO2)
Pyrite
Iron Disulfide (FeS2)
Goethite / Limonite Concretion
Iron Hydroxide Oxide (FeO(OH))
Apache Tears (Obsidian)
Hydrated Volcanic Glass (Amorphous SiO2 + H2O)
Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with impurities)
Raw black tourmaline (likely schorl)
Schorl, a sodium–iron tourmaline; approximate formula NaFe²⁺₃Al₆(BO₃)₃Si₆O₁₈(OH)₄
Blue Quartz (specifically Dumortierite Quartz)
Silicon Dioxide (SiO2) with inclusions of Dumortierite (Al7BO3(SiO4)3O3)