Common Opal with Host Rock
Opal (Hydrated silica, SiO2·nH2O)
mineral
Category
Organic (Non Rock)
Browse organic (non rock) specimens identified by the Rock Identifier community.
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Obsidian
Volcanic Glass (Amorphous Silica)
igneous
Shale
Mudstone (composed primarily of clay minerals like kaolinite, illite, and smectite, with quartz and calcite)
sedimentary
Shale or Siltstone
Sedimentary Rock (Siliciclastic)
sedimentary
Quartzite
Metamorphic Quartz Rock (SiO2)
metamorphic
Eclogite
Eclogite (Pyrope garnet and Omphacite pyroxene)
metamorphic
Quartzite Cobble
Metamorphosed Sandstone (SiO2)
metamorphic
Chert Concretion / Nodule
Microcrystalline Quartz (SiO2)
sedimentary
Fossilized Shark Tooth
Chondrichthyes (class)
fossil
Black Limestone with Calcite Veins
Limestone (Calcium Carbonate, CaCO3)
sedimentary
Quartzite
Metamorphic Quartzite (SiO2)
metamorphic
Obsidian
Obsidian (volcanic glass)
igneous
Bituminous Coal
Organic Sedimentary Rock (Carbon-based)
sedimentary
Obsidian
Volcanic Glass (SiO2)
igneous
Obsidian
Volcanic Glass (High silica amorphous rock)
igneous
Ferruginous Quartz
Silicon Dioxide (SiO2) with Hematite/Limonite impurities
mineral
Anthracite Coal
Anthracite (Carbon-based metamorphic rock)
metamorphic
Quartzite Cobble
Metamorphic Quartz-rich Rock (SiO2)
metamorphic
Quartzite
Quartzite (primarily SiO2)
metamorphic
Greenstone / Glauconitic Siltstone
Metabasalt or Glauconite-rich Sedimentary Rock
metamorphic or sedimentary
Quartzite pebble
Metamorphic rock (mainly SiO2)
metamorphic
Fossilized tooth, likely a mammalian tooth fragment
Indeterminate fossil tooth; possibly an ungulate or carnivoran tooth
fossil
Shale
Shale (composition varies: primarily clay minerals and quartz)
sedimentary
Quartzite
Quartzite (SiO2)
metamorphic
Quartzite
Quartzite (composed primarily of SiO2)
metamorphic
Siltstone
Siltstone (primarily composed of quartz and clay minerals)
sedimentary
Chert (Yellow/Tan Variety)
Chert (SiO2)
sedimentary
Bituminous Coal (with Anthracite or Vitrinite inclusion)
Organic-rich Sedimentary Rock (Carboniferous classification)
sedimentary
Unakite
Epidotized Granite
metamorphic
Chert (Yellow Jasper)
Microcrystalline Quartz (SiO2)
sedimentary
Chert Nodules in Sedimentary Rock
Microcrystalline Quartz (SiO2) within Clastic Matrix
sedimentary
Sandstone
Arenite
sedimentary
Chert (Jaspery variety)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (White Chert/Flint)
Silicon Dioxide (SiO2)
sedimentary
Fossiliferous Limestone
Biogenic Limestone with Brachiopod/Crinoid fragments
sedimentary
Chert (often called Flint)
Chert (Microcrystalline or cryptocrystalline Silica, SiO2)
sedimentary
Chert (Flint Nodules)
Chert (Silicon Dioxide, SiO2)
sedimentary
Chert Concretion with Iron Oxide Staining
Microcrystalline Quartz (SiO2)
sedimentary
Coal
Bituminous Coal (organic sedimentary rock)
sedimentary
Bituminous Coal
Bituminous coal (Organic Sedimentary Rock)
sedimentary
Bituminous Coal
Organic Sedimentary Rock (Carbon-based)
sedimentary
Amber (Cherry Amber)
Succinite (C10H16O)
Organic Gemstone