Anthracite Coal
Anthracite (Carbon-rich metamorphic coal)
metamorphic
Category
Amorphous Solid
Browse amorphous solid specimens identified by the Rock Identifier community.
Coquina
Biogenic Limestone (Calcium Carbonate, CaCO3)
sedimentary
Blue Goldstone
Aventurine Glass (Silicon Dioxide infused with Cobalt/Copper)
Synthetic (Man-made Glass)
Moqui Marble (Shaman Stone)
Ironstone Concretion (Fe2O3 - Hematite/Goethite shell with Sandstone core)
sedimentary
Mahogany Obsidian
Volcanic Glass with Hematite/Magnetite inclusions (SiO2 + Fe2O3)
Igneous
Chrysocolla in Cuprite (Sonoran Sunrise)
Cu2-xAlx(H2-xSi2O5)(OH)4·n(H2O) (Chrysocolla) and Cu2O (Cuprite)
mineral
Obsidian
Volcanic Glass (SiO2 + impurities)
igneous
Amber
Succinite (Approximate formula: C10H16O)
mineral
Amber
Succinate (Fossilized Tree Resin)
mineraloid
Amber
Succinite (Formula: C10H16O)
mineral
Obsidian
Obsidian (Volcanic Glass)
igneous
Ironstone (Limonitic Sandstone)
Ferruginous Sandstone (rich in Limonite: FeO(OH)·nH2O)
sedimentary
Terracotta (Man-made ceramic brick fragment)
Baked clay / High-iron ceramic (Silicate-based ceramic)
Anthropogenic material (Man-made sedimentary mimic)
Opalite
Opalescent Glass (SiO2 + coloring agents)
Mineral (Synthetic/Man-made)
Ambergris
Ambra grisea
Organic (often found by beachcombers)
Moqui Marble (Ironstone Concretion)
Goethite/Hematite Concretion (Fe2O3 / FeO(OH))
sedimentary
Apache Tear
Obsidian (Hydrated Volcanic Glass)
igneous
Amber
Succinite (specifically for Baltic amber; general formula C10H16O)
Mineraloid (Organic)
Chrysocolla in Quartz (Gem Silica)
Cu2-xAlx(H2-xSi2O5)(OH)4·nH2O (Chrysocolla) / SiO2 (Quartz)
mineral
Limonite (Iron Ore)
Limonite (FeO(OH)·nH2O)
mineral
Goldstone
Not a natural mineral or rock. It is an ornamental glass.
Manufactured Glass (Simulant)
Snowflake Obsidian
Spherulitic Obsidian (primarily SiO2 with Cristobalite inclusions)
igneous
Vesicular Basalt with Quartz/Chalcedony
Vesicular Basalt (primarily Plagioclase, Pyroxene, and Olivine with SiO2 infill)
igneous
Chrysocolla on Matrix
Hydrated copper phyllosilicate mineral (Cu,Al)2H2Si2O5(OH)4·nH2O
mineral
Limonite (also known as Yellow Ochre or Brown Hematite)
Limonite (Hydrated iron oxide-hydroxide, FeO(OH)·nH2O)
Mineral
Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
igneous
Dendritic Opal
Hydrated Silica (SiO2·nH2O) with Manganese or Iron Oxide inclusions
mineral
Snowflake Obsidian
Vitreous volcanic silicate (SiO2 with Cristobalite inclusions)
Igneous
Ironstone Concretion (Limonite/Goethite)
Ferruginous Sandstone or Limonite (FeO(OH)·nH2O)
sedimentary
Chrysocolla
Hydrated copper silicate - Cu2-xAlx(H2-xSi2O5)(OH)4·nH2O
mineral
Goldstone
Avventurina (Cu + SiO2 glass)
mineral
Pumice
Vesicular volcanic glass
igneous
Pumice
Pumicite
igneous
Obsidian
Obsidian (Volcanic Glass, ~70% SiO2)
igneous
Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
Igneous
Obsidian
Volcanic Glass (SiO2 + impurities)
igneous
Obsidian
Obsidian (volcanic glass), predominantly amorphous SiO₂
Igneous
Blue Goldstone
Synthetic Avanturine Glass (or Aventurine Glass)
Synthetic Glass
Chert (Common Opal variant)
Silicon Dioxide (SiO2)
sedimentary
Mahogany Obsidian
Volcanic Glass (with inclusions of Magnetite or Hematite)
igneous
Ironstone Concretion (Limonite/Hematite Nodules)
Ironstone (principally Limonite FeO(OH)·nH2O or Hematite Fe2O3 mixed with silica/clay)
sedimentary
Dragon Stone
Ohko Stone (Argillaceous sedimentary rock)
sedimentary