Siltstone
Siltstone (Detrital Sedimentary Rock)
sedimentary
Category
Industrial Byproduct (Often Mistaken For Obsidian Or Mineral)
Browse industrial byproduct (often mistaken for obsidian or mineral) specimens identified by the Rock Identifier community.
Learn about Industrial Byproduct (Often Mistaken For Obsidian Or Mineral) in the encyclopedia
View all →
Felted Quartz / Chlorite Quartz
Chlorite included Quartz (SiO2 + (Mg,Fe)3(Si,Al)2O5(OH)4)
mineral
Obsidian
Volcanic Glass (Amorphous Silicon Dioxide)
igneous
Obsidian
Obsidian (Volcanic Glass, SiO2 + impurities)
igneous
Obsidian
Obsidian (Amorphous volcanic glass)
igneous
Concretion
Septarian Concretion (Fragmentary)
sedimentary
Banded Sedimentary Rock (Siltstone/Mudstone with concretion)
Siltstone with Ferruginous Banding
sedimentary
Obsidian
Volcanic Glass (Amorphous Silica)
igneous
Limonite Concretion (Ironstone)
Limonite (FeO(OH)·nH2O) / Goethite
sedimentary
Blue Dumortierite Quartz
Dumortierite in Quartz (AlAl6BSi3O18)
metamorphic
Mahogany Obsidian
Volcanic glass containing Magnetite/Hematite
igneous
Obsidian (likely snowflake-free black volcanic glass)
Volcanic glass; predominantly rhyolitic silica melt (SiO₂-rich, noncrystalline)
igneous
Sandstone Concretion
Clastic Sedimentary Concretion (SiO2 with Iron Oxide)
sedimentary
Mahogany Obsidian
Volcanic Glass (with inclusions of Magnetite or Hematite)
igneous
Quartz (Iron-stained)
Silicon Dioxide (SiO2)
mineral
Obsidian
Obsidian (Volcanic Glass, primarily SiO2)
igneous
Obsidian
Volcanic glass
igneous
Milky Quartz with Mica Matrix
SiO2 (Silicon Dioxide) with Muscovite/Biotite mica
mineral
Obsidian
Volcanic Glass (predominantly SiO2)
igneous
Chert (Jasper)
Microcrystalline Quartz (SiO2)
sedimentary
Sandstone (likely River-tumbled Picture Sandstone)
Arenite (predominantly SiO2 with iron oxide impurities)
sedimentary
Yellow Calcite
Calcium Carbonate (CaCO3)
mineral
Sandstone (Micaceous Sandstone)
Arenite (SiO2 with KAl2(AlSi3O10)(OH)2 inclusions)
sedimentary
Quartzite with inclusions
Quartzite (SiO2)
metamorphic
Ferruginous Siltstone or Mudstone
Ferruginous Siltstone / Goethitic Sandstone
sedimentary
Obsidian
Obsidian (Volcanic Glass)
igneous
Obsidian
Volcanic Glass (SiO2)
igneous
Obsidian
Obsidian (Volcanic Glass)
igneous
Obsidian
Amorphous volcanic glass (primarily SiO2)
igneous
Obsidian
Obsidian (Volcanic Glass)
igneous
Obsidian
Obsidian (volcanic glass), predominantly Silicon Dioxide (SiO2)
igneous
Snowflake Obsidian
Volcanic Glass with Cristobalite inclusions (SiO2)
igneous
Obsidian (Apache Tear)
Volcanic Glass (High-silica Rhyolite)
igneous
Raw black tourmaline (likely schorl)
Schorl, a sodium–iron tourmaline; approximate formula NaFe²⁺₃Al₆(BO₃)₃Si₆O₁₈(OH)₄
mineral
Ferruginous Quartz (Iron-Stained Quartz)
Silicon Dioxide (SiO2) with Iron Oxide inclusions
mineral
Chalcopyrite in Quartz (Gold Ore Matrix)
CuFeS2 (Chalcopyrite) with SiO2 (Quartz)
mineral
Black Spinel
Magnesium Aluminum Oxide (MgAl2O4)
mineral
Blue Apatite
Fluorapatite (Ca5(PO4)3F)
mineral
Limonite Concretion
Limonite (Hydrated Iron Oxide) FeO(OH)·nH2O
sedimentary
Mahogany Obsidian
Volcanic Glass with Hematite/Magnetite inclusions
igneous
Sodalite
Na8(Al6Si6O24)Cl2
mineral
Aventurine
Silicon Dioxide (SiO2) with inclusions
metamorphic