Moldavite
Tektite (Impact Glass), ~80% SiO2 + Al2O3
tektite
Category
Amorphous Solid
Browse amorphous solid specimens identified by the Rock Identifier community.
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Obsidian
Volcanic Glass (predominantly SiO2)
igneous
Obsidian
Obsidian (Volcanic Glass)
igneous
Opalite (Synthetic Moonstone/Opal)
Synthetic Silica Glass
mineraloid (synthetic)
Fulgurite
Fulgurite (Lechatelierite-rich variety)
metamorphic
Coquina
Bioclastic Limestone
sedimentary
Common Opal in Host Rock
Hydrated Silica (SiO2·nH2O)
mineraloid
Amber
Succinite (fossilized resin)
mineral
Petrified Wood
Silicified Wood (SiO2)
sedimentary
Snowflake Obsidian
Vitreous volcanic silicate (SiO2 with Cristobalite inclusions)
igneous
Amber
Succinite (specifically for Baltic amber); approximate formula C10H16O
Mineraloid
Anthracite Coal
Anthracite
metamorphic
Amber (with potentially inclusions)
Succinite (Fossilized Tree Resin)
Mineraloid
Amber
Succinite (specifically for Baltic amber); Fossilized Tree Resin (C10H16O)
Organic Mineraloid
Limonite (often after Pyrite)
Limonite (FeO(OH)·nH2O)
mineral
Amber (specifically Cherry Amber)
Succinite (with the chemical formula C10H16O)
Organic Gemstone (not a mineral)
Limonite
Limonite (Hydrous iron oxides, predominantly Goethite FeO(OH)·nH2O)
mineral
Amber
Succinite (Fossilized Tree Resin)
mineraloid
Obsidian
Volcanic glass (SiO2-rich)
igneous
Obsidian
Volcanic glass (primary composition: SiO2)
igneous
Anthracite Coal
Anthracite (Carbon C)
metamorphic
Tektite (Indochinite)
Tektite (Natural silica glass)
igneous
Anthracite Coal
Anthracite (Carbon)
sedimentary
Obsidian
Volcanic Glass (SiO2)
igneous
Obsidian
Obsidian (Volcanic Glass)
igneous
Petrified Wood
Silicified Wood (SiO2)
sedimentary
Amber
Succinicum (Organic compound, primarily C10H16O)
Organic Gemstone (Mineraloid)
Anthracite Coal
Anthracite (Carbon-rich metamorphic sedimentary rock)
sedimentary
Limonite Concretion (Goonie or Rattlestone)
Limonite (FeO(OH)·nH2O)
sedimentary
Copper Ore with Malachite and Chrysocolla
Cu2CO3(OH)2 (Malachite) with Cu2-xAlx(H2-xSi2O5)(OH)4·nH2O (Chrysocolla)
mineral
Anthracite Coal
Anthracite
metamorphic
Limonite (Iron Stone/Goethite)
Limonite (mixture of hydrated iron oxides, primarily Goethite: α-FeO(OH))
mineral
Obsidian (Black)
Obsidian (approx. 70–75% SiO2)
igneous
Amber
Succinite (fossilized resin); C10H16O
mineraloid
Coal (likely Anthracite)
Anthracite coal
sedimentary
Coquina
Bioclastic Limestone (CaCO3)
sedimentary
Obsidian
Extrusive igneous volcanic glass
igneous
Obsidian
Volcanic Glass (Primary composition: SiO2 - Silicon Dioxide)
igneous
Limonite
Limonite (FeOO·nH2O)
mineral
Blue Obsidian
Volcanic Glass (SiO2 with inclusions)
igneous
Pumice
Highly vesicular rhyolite/dacite (Amorphous glass)
igneous
Opal
Hydrated amorphous form of silica (SiO2·nH2O)
mineral