Obsidian
Volcanic Glass (SiO2)
igneous
Category
Mineraloid
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Obsidian
Volcanic Glass (predominantly SiO2, approximately 70% or more)
igneous
Snowflake Obsidian
Obsidian with Spherulitic Cristobalite (SiO2)
igneous
Mahogany Obsidian
Obsidian (SiO2 + Fe2O3)
igneous
Limonite (Iron Ore)
Hydrous ferric oxides (FeO(OH)·nH2O)
mineral
Mahogany Obsidian
Volcanic Glass with Hematite/Magnetite (SiO2 + Fe2O3)
igneous
Obsidian
Volcanic Glass (Silicon Dioxide with impurities)
igneous
Obsidian
Obsidian (Amorphous volcanic glass, SiO2 with impurities)
igneous
Snowflake Obsidian
Volcanic glass containing Spherulites (SiO2)
igneous
Amber
Succinite (with a generalized formula of C10H16O)
mineral
Limonite (Ironstone) Concretion
FeO(OH)·nH2O (Hydrous ferric oxide)
sedimentary
Obsidian
Obsidian (Volcanic Glass)
igneous
Snowflake Obsidian
Volcanic Glass with Spherulite inclusions (Chemical composition: 70–75% SiO2 + MgO, Fe3O4)
igneous
Obsidian (Black Obsidian)
Obsidian (Volcanic Glass)
igneous
Black Opal (Triplet)
Hydrated Silica (SiO2·nH2O)
mineral
Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with impurities)
igneous
Common Opal with Host Rock
Opal (Hydrated silica, SiO2·nH2O)
mineral
Mahogany Obsidian
Obsidian (volcanic glass with hematite/magnetite inclusions)
igneous
Precious Opal
Hydrated Silica (SiO2·nH2O)
mineral
Obsidian
Obsidian (Extrusive Volcanic Glass)
igneous
Obsidian
Volcanic Glass (comprised primarily of SiO2)
Igneous
Opalite
Synthetic Glass (Hydrated Crystalline Silicon Dioxide simulation)
mineral
Mahogany Obsidian
Volcanic glass (SiO2 + Fe2O3)
igneous
Black Obsidian
Volcanic Glass (predominantly SiO2, Silicon Dioxide)
igneous
Limonite (Yellow Ochre)
Limonite (an amorphous mixture of hydrated iron oxides, primarily FeO(OH)·nH2O)
mineral
Snowflake Obsidian
Volcanic Glass (spherulitic Obsidian) - SiO2 (with Cristobalite inclusions)
igneous
Limonite with Quartz (Gossan)
Hydrated iron(III) oxide-hydroxide mixture (FeO(OH)·nH2O) with Silicon Dioxide (SiO2)
Mineral
White Opal (Common)
Hydrated Silica (SiO2·nH2O)
mineral
Black Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
igneous
Limonite and Goethite (Ironstone)
Hydrous Iron Oxide Mixture (FeO(OH)·nH2O)
sedimentary
Obsidian
Volcanic Glass (Primary composition: SiO2 - Silicon Dioxide)
igneous
Obsidian
Obsidian (principally SiO2 with MgO and Fe3O4)
igneous
Tektite (likely Australite)
Tektite (no specific chemical formula as it's a natural glass of variable composition, mostly SiO2, Al2O3, FeO, MgO, CaO, K2O, Na2O, TiO2)
Mineral (specifically a mineraloid)
Limonite (Iron Ore)
Limonite (an FeO(OH)·nH2O mineraloid, not a true mineral due to variable composition)
Mineral
Amber
Succinite (specifically for Baltic amber); C10H16O (Variable organic compound)
mineral
Mahogany Obsidian Arrowhead
Volcanic Glass with Hematite/Magnetite inclusions (Amorphous Silicon Dioxide)
igneous
Amber
Amber (Fossilized Tree Resin)
Mineral
Red Sandstone
Clastic Sedimentary Mineraloid (predominantly Quartz grains with Iron Oxide cement)
sedimentary
Amber
Succinate (Succinite for Baltic varieties)
Organic Mineraloid
Synthetic Convention Badge (Plastic/PVC)
Polyvinyl Chloride (PVC) / Polycarbonate
mineraloid (synthetic)
Amber
Succinite (fossilized tree resin)
Organic Mineraloid
Man-made Glass (Tumbled/Shaped)
Amorphous Silicon Dioxide (SiO2) with metal oxide colorants
Mineraloid (synthetic)