Red Coral
Corallium rubrum (Calcium Carbonate, CaCO3)
Organic Gemstone (Sedimentary classification)
Category
Amorphous Solid
Browse amorphous solid specimens identified by the Rock Identifier community.
Obsidian
Obsidian (principally SiO2)
igneous
Ironstone Concretion (Moqui Marble Type)
Goethite/Hematite-cemented Sandstone Concretion
sedimentary
Ironstone Concretion / Limonite Node
Ferruginous Sedimentary Rock (composed primarily of Limonite FeO(OH)·nH2O and Goethite)
sedimentary
Limonite with Trace Fossils
Hydrous Iron Oxide Mixture (FeO(OH)·nH2O)
sedimentary
Coal (most likely Bituminous or Anthracite)
Coal (organic sedimentary rock)
Sedimentary
Pumice
Pumice (Vesicular felsic extrusive igneous rock)
igneous
Limonite and Goethite encrusted Chert/Ironstone
Hydrated Iron Oxide (FeO(OH)·nH2O) with cryptocrystalline Silica (SiO2)
sedimentary
Scoria (Lava Rock)
Scoria
igneous
Pumice
Vesicular Rhyolite / Glassy Igneous Rock
igneous
Pumice
Vesicular Rhyolite or Dacite Pumice (Amorphous volcanic glass)
igneous
Slag
Ferrous Slag (Amorphous calcium-magnesium-aluminum silicates)
igneous (artificial/anthropogenic)
Amber
(C10H16O)n – an amorphous organic substance, primarily composed of polymerized isoprenoids.
Mineral
Pearl (with Peridot)
Calcium carbonate (CaCO3) + Conchiolin; Peridot: Magnesium iron silicate (Mg, Fe)2SiO4
mineral
Limonite (after Pyrite Pseudomorph)
Limonite (Hydrated Iron Oxide Mixture, FeO(OH)·nH2O)
mineral
Yellow Quartz Pebble
Quartz (Silicon Dioxide - SiO2)
mineral
Conglomerate (Asphaltic/Anthropogenic)
Clastic sedimentary rock / Bituminous mixture
sedimentary
Slate
Slate (a fine-grained, foliated metamorphic rock). Mineral composition: Primarily composed of mica minerals (muscovite, chlorite, sericite) and quartz, with minor amounts of hematite, pyrite, and other accessory minerals.
sedimentary
Ironstone Concretion (likely)
Goethite/Hematite/Limonite cemented sediment
Sedimentary Rock
Pumice
Vesicular volcanic glass (primarily SiO2 with Al2O3)
Igneous
Obsidian
Volcanic glass
igneous
Pumice
Vesicular Rhyolite or Dacite
igneous
Chrysocolla in Malachite
Cu2CO3(OH)2 (Malachite) / Cu2-xAlx(H2-xSi2O5)(OH)4·nH2O (Chrysocolla)
mineral
Opalite (Man-made Glass)
Fused glass (typically made of dolomite and metal opacifiers)
Man-made Material / Glass
Slag (Industrial Glass/Metal Waste)
Artificial silicate/ferro-silicate byproduct
Mineraloid (Industrial byproduct)
Pumice
Pumice (a volcanic glass, primarily SiO2 with Al2O3)
igneous
Synthetic Resin / Plastic Figurine
Synthetic Polymer (Copolymer of Polyethylene or Resin)
Mineraloid-like Synthetic Material
Orange Tabby (Felis catus)
Felis silvestris catus (variety: Red Mackerel Tabby)
Organic/Biological specimen (Non-Mineral)
Smoky Quartz
Quartz (SiO₂)
Mineral
Obsidian (likely Golden Sheen Obsidian or Rainbow Obsidian, given the subtle sheen visible on some beads)
Obsidian (volcanic glass, predominantly SiO2 with various impurities)
Igneous
Obsidian / Volcanic Glass
Obsidian (principally SiO2, usually 70% or more)
igneous
Limonite and Goethite encrusted Quartz (Iron-stained Gossan)
FeO(OH)·nH2O (Limonite) / FeO(OH) (Goethite) on SiO2 (Quartz)
mineral
Coquina
Bioclastic Limestone (composed primarily of CaCO3)
sedimentary
Ironstone Nodule (Ironstone Concretion)
Siderite-rich Mudstone (FeCO3) or Limonite (FeO(OH)·nH2O)
sedimentary
Goldfish Cracker (Culinary Mimic)
Cibus aurum (Commonly composed of Enriched Wheat Flour and Cheddar Cheese)
Anthropogenic Sedimentary-style Organic Solid
Amber
Amber (Fossilized Tree Resin)
Mineral
Pink Anthracite Coal (dyed)
Anthracite Coal (Artificially Colored)
Sedimentary Rock (Altered)
Opalite (a synthetic glass, often confused with Opal)
Silicon dioxide glass (SiO2nH2O, for natural opal)
Synthetic (glass)
Anthracite Coal
Anthracite (a variety of coal, predominantly carbon)
Sedimentary Rock (Metamorphosed)
Coral (Precious Coral)
Corallium rubrum (Red Coral), Paracorallium japonicum (Momo Coral), Pleurocorallium elatius (Sardinian Coral), various other species within the Corallidae family. Chemically, it's primarily Calcium Carbonate (CaCO 3 ).
Mineral, Organic Gemstone
Amber (Copal)
Organic gemstone, fossilized tree resin (often immature amber or copal)
Mineral
Obsidian
Obsidian (volcanic glass)
igneous