Obsidian
Extrusive igneous volcanic glass (rich in SiO2)
igneous
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.
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Obsidian
Volcanic Glass (SiO2)
igneous
Obsidian
Volcanic Glass (SiO2 rich)
igneous
Milky Quartz with Dendritic Inclusions
Silicon Dioxide (SiO2) with impurities
mineral
Dumortierite Quartz
Dumortierite-bearing Quartz (SiO2 with Al7BO3(SiO4)3O3)
mineral
Taaffeite
BeMgAl4O8 (Beryllium Magnesium Aluminum Oxide)
mineral
Milky Quartz or Calcite Pebble
Silicon Dioxide (SiO2) or Calcium Carbonate (CaCO3)
mineral
Ironstone concretion
Siderite or Limonite-rich Concretion (FeO(OH)·nH2O)
sedimentary
Concretion (Sandstone)
Carbonate-cemented Sandstone Concretion
sedimentary
Pyrite in Quartzite/Graphite Matrix
Iron Sulfide (FeS2)
Mineral
Quartzite River Rock with Dendrites
Metamorphosed Quartz-rich Sandstone with Manganese Oxide (MnO2) inclusions
metamorphic
Black drusy mineral coating, possibly hematite or manganese oxide
Undetermined; likely microcrystalline hematite (Fe₂O₃) or manganese oxides such as pyrolusite (MnO₂)
mineral
Snowflake Obsidian
Volcanic glass with Cristobalite inclusions (mostly SiO2)
igneous
Obsidian (likely Golden Sheen Obsidian or Rainbow Obsidian, given the subtle sheen visible on some beads)
Obsidian (volcanic glass, predominantly SiO2 with various impurities)
Igneous
Black tourmaline (likely schorl)
Schorl, sodium–iron tourmaline: NaFe²⁺₃Al₆(BO₃)₃Si₆O₁₈(OH)₄
mineral
Sandstone Concretion
Clastic Sedimentary Concretion (primarily SiO2 with Fe2O3 cement)
sedimentary
Iron Concretion
Ferruginous concretion (Fe2O3·nH2O / FeO(OH))
sedimentary
Mahogany Obsidian
Obsidian (Volcanic Glass) with Hematite/Magnetite inclusions
igneous
Obsidian
Obsidian (Volcanic Glass, SiO2 dominated)
igneous
Mahogany Obsidian
Volcanic glass (SiO2 + Fe2O3)
igneous
Sandstone with Liesegang Rings
Clastic Sedimentary Rock with Iron Oxide Precipitates (SiO2 + Fe2O3)
sedimentary
Banded Sandstone
Arenite (with iron oxide banding)
sedimentary
Variscite in Matrix
Variscite (AlPO4 · 2H2O)
mineral
Tumbled black tourmaline
Schorl tourmaline, NaFe3Al6(BO3)3Si6O18(OH)4
mineral
Obsidian
Obsidian (principally SiO2 + MgO, Fe3O4)
igneous
Apatite
Apatite Group (e.g., Fluorapatite Ca5(PO4)3F, Chlorapatite Ca5(PO4)3Cl, Hydroxylapatite Ca5(PO4)3(OH))
mineral
Obsidian
Volcanic glass (SiO2 + impurities)
igneous
Obsidian
Extrusive igneous volcanic glass
igneous
Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
igneous
Ambergris
Ambra grisea (Metabolic byproduct)
Organic (Geological relative)
Perlite (Unexpanded)
Amorphous volcanic glass
igneous
Dendritic Agate
Silicon Dioxide (SiO2) with Manganese/Iron oxide inclusions
mineral
Flesh-colored Quartz Mineral
SiO2 (Silicon Dioxide) with Iron Impurities
mineral
![Arfvedsonite in Quartz (Arfvedsonite [Na3(Fe2+4Fe3+)Si8O22(OH)2] often hosted in Quartz or Feldspar) — igneous](https://media.rockidentification.com/5af4c6b0-6733-4f77-a6ae-987848327128-thumbnail.jpg)
Arfvedsonite in Quartz
Arfvedsonite [Na3(Fe2+4Fe3+)Si8O22(OH)2] often hosted in Quartz or Feldspar
igneous
Mahogany Obsidian
Volcanic Glass (SiO2 + Fe2O3)
igneous
Blue Dumortierite Quartz
Dumortierite in Quartz (AlAl6BSi3O12(O,OH)3)
mineral
Dendritic Limestone
Calcite with Manganese Oxide (Manganese Dendrites)
sedimentary
Chrysoprase
Chalcedony (Silicon Dioxide, SiO2), flavored by Nickel
mineral
Dumortierite Quartz
Al7BO3(SiO4)3O3 (Aluminum borate silicate)
mineral
Sodalite
Na8(Al6Si6O24)Cl2
mineral
Black tumbled stone, possibly obsidian
Volcanic glass; primarily SiO₂, if obsidian
igneous
Red Jasper
Silicon Dioxide (SiO2) - Microcrystalline Quartz
sedimentary