Black Obsidian
Volcanic Glass (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 (predominantly SiO2)
igneous
Tumbled smoky quartz (probable)
Quartz, silicon dioxide (SiO₂), colored by irradiation and trace aluminum
mineral
Dumortierite Quartz
Dumortierite in Quartz (Al6O3(BO3)(SiO4)3)
mineral
Ironstone Nodules (Iron Concretion)
Siderite or Hematite Concretion
sedimentary
Tiger's Eye, Hematite, and Black Obsidian Bracelet
SiO2 (Tiger's Eye), Fe2O3 (Hematite), and 70-75% SiO2 (Obsidian)
mineral
Dumortierite Quartz (Blue Quartz)
Al7BO3(SiO4)3O3 with Quartz (SiO2)
mineral
Polished mahogany obsidian (likely)
Volcanic glass; primarily silica-rich rhyolitic glass (SiO₂), with iron oxides
igneous
Carborundum (Silicon Carbide)
Silicon Carbide (SiC)
mineral (synthetic)
Snowflake Obsidian and Green Aventurine
Volcanic Glass (SiO2 with Cristobalite inclusions) and Quartz (SiO2 with Fuchsite)
igneous and metamorphic
Obsidian (black volcanic glass), possibly slag or basalt
Obsidian; chiefly amorphous volcanic silica glass, approximately SiO₂-rich rhyolitic composition
igneous
Quartz Pebble (with Manganese dendrites/staining)
Silicon Dioxide (SiO2) with Manganese Oxide impurities
mineral
Mahogany Obsidian
Volcanic Glass with Hematite inclusions (SiO2 + Fe2O3)
igneous
Manganese Dendrite on Siltstone
Manganese Oxide (pyrolusite or psilomelane) Dendrites
mineral/sedimentary
Cone-in-cone structure (Limestone)
Cone-in-cone structure (Secondary Sedimentary Structure)
sedimentary
Apache Tear (Obsidian)
Obsidian
Igneous
Obsidian
Obsidian (Volcanic Glass, SiO2)
igneous
Obsidian
Volcanic Glass (Amorphous Silica)
igneous
Black Obsidian
Volcanic Glass (SiO2)
igneous
Obsidian
Obsidian (volcanic glass)
igneous
Sheen Obsidian
Volcanic glass (SiO2 with inclusions)
igneous
Tiffany Stone
Bertrandite-Bearing Fluorite Hyalite Opal
metamorphic
Dumetierite in Quartz (Blue Quartz)
Dumortierite (Al7BO3(SiO4)3O3) inclusions in Quartz (SiO2)
metamorphic
Mahogany Obsidian
Volcanic Glass with Hematite inclusions
igneous
Siltstone with iron staining
Siltstone (primarily SiO2 with FeO(OH) coatings)
sedimentary
Dendritic sandstone
Sandstone with Manganese Oxide dendrites
sedimentary
Quartzite
Quartzite (SiO2)
metamorphic
Ambergris
Ambra grisea (Metabolic byproduct)
Organic (Geological relative)
Sandstone (Ferruginous Concretion)
Ferruginous Sandstone Concretion / SiO2 with Fe2O3 cement
sedimentary
Obsidian
Amorphous volcanic glass (primarily SiO2)
igneous
Polished black stone, likely black obsidian
Obsidian (volcanic glass; predominantly silica-rich SiO₂)
igneous
Silver (Jewelry form)
Native Silver (Ag)
mineral
Chert Concretion (Flint)
Silicon Dioxide (SiO2)
sedimentary
Manganese-coated Sandstone
Clastic sedimentary rock with Manganese Oxide (often Pyrolusite or Psilomelane)
sedimentary
Ironstone Nodules (Limonite/Hematite)
Goethite/Hematite mix (FeO(OH)/Fe2O3)
sedimentary
Chert (Jasper/Flint variety)
Microcrystalline Quartz (SiO2)
sedimentary
Yellow Aventurine
Quartzite with inclusions (SiO2)
metamorphic
Green Aventurine
Silicon Dioxide (SiO2) with Fuchsite inclusions
metamorphic
Obsidian
Volcanic Glass (Amorphous Silicon Dioxide)
igneous
Siltstone/Sandstone (possibly Wonderstone or Picture Sandstone)
Clastic Sedimentary Rock (primarily SiO2 with Iron Oxide inclusions)
Sedimentary
Sandstone Concretion
Ferruginous Sandstone Concretion
sedimentary
Quartzite
Quartzite (primarily SiO2)
metamorphic