Limonite Concretion
Hydrated iron(III) oxide-hydroxide (FeO(OH)·nH2O)
sedimentary
Category
Organic Crystal (Mineraloid)
Browse organic crystal (mineraloid) specimens identified by the Rock Identifier community.
Snowflake Obsidian
Spherulitic Volcanic Glass (SiO2 + impurities)
igneous
Limonite (Iron Ore)
Limonite (an FeO(OH)·nH2O mineraloid, not a true mineral due to variable composition)
Mineral
Snowflake Obsidian
Volcanic glass containing Spherulites (SiO2)
igneous
Mahogany Obsidian
Volcanic Glass with Hematite/Magnetite (SiO2 + Fe2O3)
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/Sandstone mixture)
Limonite (FeO(OH)·nH2O) often mixed with Goethite and sedimentary matrix
mineral
Yellow Ocher (Limonite)
Limonite (Hydrated Iron Oxide) - FeO(OH)·nH2O
mineral
Obsidian
Obsidian (Volcanic Glass, SiO2 + impurities)
igneous
Obsidian
Volcanic Glass (SiO2 + impurities)
igneous
Naga Silver-Inlaid Ebony and Bone/Horn Beads
Diospyros (Ebony) or Keratin (Horn) with Silver/White-Metal Inlay
Organic (Anthropological Artifact)
Mahogany Obsidian Arrowhead
Volcanic Glass with Hematite/Magnetite inclusions (Amorphous Silicon Dioxide)
igneous
Mahogany Obsidian
Volcanic glass containing Magnetite/Hematite
igneous
Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
igneous
Obsidian (Black Obsidian)
Obsidian (Volcanic Glass)
igneous
Snowflake Obsidian
Volcanic Glass with Spherulite inclusions (Chemical composition: 70–75% SiO2 + MgO, Fe3O4)
igneous
Black Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
igneous
Opalite
Synthetic Glass (Hydrated Crystalline Silicon Dioxide simulation)
mineral
Obsidian
Volcanic Glass (Primary composition: SiO2 - Silicon Dioxide)
igneous
Limonite with Quartz (Gossan)
Hydrated iron(III) oxide-hydroxide mixture (FeO(OH)·nH2O) with Silicon Dioxide (SiO2)
Mineral
Limonite and Goethite (Ironstone)
Hydrous Iron Oxide Mixture (FeO(OH)·nH2O)
sedimentary
Ambergris
Ambrein (C30H52O)
mineraloid / organic geological substance
Black Limestone with Calcite Veining
Bituminous Limestone (CaCO3 with Organic Carbon inclusions)
sedimentary
Amber
Succinicum (C10H16O)
mineral
Amber and Citrine Quartz
Succinite (Amber) and Silicon Dioxide (SiO2 / Citrine)
mineral
Ambergris
Physeter macrocephalus excreta (Ambergris)
mineraloid / organic geological find
Amber
Succinite (fossilized resin, C10H16O)
mineral
Ironstone concretion / Limonitic Sandstone
Goethite/Hematite Cemented Sandstone (Hydrated Iron Oxide)
sedimentary
Limestone (specifically Bituminous or Carbonaceous Limestone)
Calcium Carbonate (CaCO3) with Organic Impurities
sedimentary
Amber
Amber (C10H16O)
mineral
Grass (Organic Matter/Soil)
Poaceae (family of monocotyledonous flowering plants)
Organic Materia (Not a rock or mineral)
Amber
Succinite (approximate formula C10H16O)
mineral
Amber
Succinite (C10H16O)
mineral
Amber
Succinite (Approximate formula: C10H16O)
mineral
Sea Glass
Amorphous Silica (SiO2) with various additives
Mineraloid (Anthropogenic)
Moldavite
Silica glass with small amounts of aluminum, iron, and other elements
Mineraloid / Tektite
Fossilized Shell in Limestone
Bivalve fossil (CaCO3) in Carbonate Sedimentary Rock
sedimentary
Opalite (Synthetic Moonstone/Opal)
Synthetic Silica Glass
mineraloid (synthetic)
Cullet (Slag Glass)
Amorphous Silica (SiO2) with various metal oxide colorants
mineraloid / anthropogenic
Man-made Glass (Tumbled/Shaped)
Amorphous Silicon Dioxide (SiO2) with metal oxide colorants
Mineraloid (synthetic)
Yellow Jasper
Jasper (Silicon Dioxide, SiO2)
sedimentary (or mineraloid)
Opalite
Synthetic Glass, SiO2 base with metallic inclusions
mineraloid (synthetic)