Apache Tear
Obsidian (Volcanic Glass), formula: 70–75% SiO2 plus MgO, Fe3O4
igneous
Category
Amorphous Solid
Browse amorphous solid specimens identified by the Rock Identifier community.
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Blue Sapphire (Synthetic or Man-made Glass Imitation)
Corundum (Al2O3) if natural; Lead-glass or Spinal if synthetic
mineral
Mahogany Obsidian
Volcanic Glass (predominantly SiO2 with inclusions of Hematite or Magnetite)
igneous
Snowflake Obsidian
Spherulitic Volcanic Glass (primarily SiO2)
igneous
Mahogany Obsidian
Volcanic Glass (SiO2 + Fe2O3)
igneous
Ferruginous Sandstone (Ironstone)
Sedimentary rock with high iron oxide content (Fe2O3 / FeO(OH))
sedimentary
Amber
Succinite (Formula: C10H16O)
Organic Mineraloid
Anthracite Coal
Anthracite (Carbon-based sedimentary-derived metamorphic rock)
metamorphic
Pumice
Pumice (a highly vesicular extrusive igneous rock)
Igneous
Bumblebee Jasper
Calcite-bearing Volcanic Tuff containing Orpiment (As2S3) and Realgar (As4S4)
sedimentary
Anthracite
Anthracite Coal
sedimentary
Obsidian
Obsidian (principally SiO2 with MgO and Fe3O4)
igneous
Amber
Succinite (specific to Baltic amber), fossilized tree resin
mineraloid
Concrete / Anthropogenic Conglomerate
Man-made composite material (Portland cement, aggregate, and water)
not a natural rock
Apache Tear
Hydrated Obsidian (Volcanic Glass)
igneous
Pumice
Pumice (Vesicular Rhyolite/Andesite)
igneous
Anthracite Coal
Anthracite (Metamorphosed Coal)
sedimentary
Amber
Succinite (specifically for Baltic amber); chemical formula approximately C10H16O
Mineraloid
Quartz with Limonite Staining
Silicon Dioxide (SiO2) with Hydrated Iron Oxide (FeO(OH)·nH2O)
Mineral
Amber
Succinicum (Organic polymer, largely C10H16O)
Organic Mineral
Black Obsidian
Volcanic Glass (predominantly SiO2)
igneous
Obsidian
Obsidian (Volcanic Glass), primarily SiO2
igneous
Obsidian
Volcanic Glass (SiO2 + minor impurities)
igneous
Amber
Succinite (fossilized resin, C10H16O)
mineral
Ironstone Concretion / Limonite
Goethite and Limonite (FeO(OH)·nH2O)
sedimentary
Anthracite Coal
Anthracite (Carbon)
metamorphic
Bauxite
Al2O3·2H2O (principally composed of gibbsite, boehmite, and diaspore)
sedimentary
Libyan Desert Glass
Impact-melt silica glass (SiO2 + traces of Al, Fe, Ti)
mineral (Tektite/Impactite)
Bituminous Coal
Organic sedimentary rock (humic coal)
sedimentary
Anthracite Coal
Anthracite (Carbon-rich metamorphic coal)
metamorphic
Blue Goldstone
Aventurine Glass (SiO2 with Co and metallic inclusions)
mineral (synthetic glass)
Pumice
Pumice (a highly vesicular volcanic glass)
igneous
Banded Iron Formation (BIF) / Ironstone Conglomerate
Ironstone (Hematite/Goethite rich sedimentary rock)
sedimentary
Limonite (Iron Stone)
Limonite (Hydrated Iron Oxide) - FeO(OH)·nH2O
mineral
Chalcedony (Common Opal variant)
Silicon dioxide (SiO2) with varying levels of hydration
mineral
Slag (Industrial Glass/Metal)
Ferrous slag or Glassy silicate byproduct
Antropogenic rock (Man-made)
Pumice
Vesicular volcanic glass
igneous
Amber (Butterscotch/Egg Yolk Variety)
Succinite (Approx. C10H16O)
Organic Gemstone
Sea Glass (Frosted Glass)
Amorphous Silica (SiO2) with various metal oxide impurities
Man-made material (Anthro-lithic product)
Sea Glass (specifically Frosted White)
Amorphous Silica (substance: Sodium-calcium silicate glass)
Mineraloid (Anthropogenic/Man-made rock)
Boulder Opal
Precious Opal in Ironstone (Amorphous Hydrated Silica, SiO2·nH2O)
Mineral
Sea Glass
Amorphous silicon dioxide (SiO2) - Man-made glass tumbled by nature
mineral