Slag
Ferrous Slag (Siliceous industrial waste)
Anthropogenic (Man-made industrial byproduct)
Category
Amorphous Solid
Browse amorphous solid specimens identified by the Rock Identifier community.
Learn about Amorphous Solid in the encyclopedia
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Fulgurite (Sand-tube)
Fulgurite (Lechatelierite-rich fused sand)
metamorphic
Coquina or Fossilized Shell Aggregate
Calcareous bioclastic sedimentary rock (CaCO3)
sedimentary
Anthracite
Anthracite Coal (C)
sedimentary
Coal (likely Bituminous or Lignite)
Organic Sedimentary Rock (Carbonaceous)
sedimentary
Goldstone (Red)
Aventurine Glass (Cupriferous glass)
Synthetic Glass (Man-made)
Baltic Amber (Butterscotch or Egg Yolk Variety)
Succinite (chemical formula: C10H16O)
Organic Gemstone (not a rock or mineral)
Red Amber (Burmite/Cherry Amber)
Succinite / Retinite (Organic Fossilized Resin, C10H16O)
Mineraloid (Organic)
Ambergris
Ambrein (C30H52O Derivative)
Organic (Zoogenic)
Mahogany Obsidian
Volcanic glass (SiO2 + Fe2O3)
igneous
Obsidian (Black Obsidian)
Volcanic Glass (Primary composition: SiO2 - Silicon Dioxide)
igneous
White Opal (Common)
Hydrated Silica (SiO2·nH2O)
mineral
Manganese Oxide Crust on Limestone
Manganese Oxides (e.g., Pyrolusite MnO2 or Romanechite) on CaCO3
sedimentary
Amber
Fossilized Tree Resin (C10H16O)
mineral
Fulgurite
Fulgurite (Lechatelierite)
metamorphic
Chert (Yellow Jasper variant)
Microcrystalline Quartz (SiO2)
sedimentary
Blue opalite (often sold as synthetic opal)
Opalite glass; amorphous hydrated silica if natural opal (SiO₂·nH₂O)
gemstone
Coal (Bituminous)
Organic sedimentary rock primarily consisting of carbon (C)
sedimentary
Pumice
Pumice (a vesicular volcanic glass)
igneous
Sea Glass (White/Clear)
Amorphous Silica (Alkali-Lime-Silica Glass), SiO2 + Na2O + CaO
Anthropogenic (Man-made product subject to geological processes)
Carnelian
Carnelian (a variety of Chalcedony, SiO2)
Mineral
Vesicular Basalt with Opal or Quartz
Vesicular Basalt (Amorphous SiO2.nH2O if Opal)
igneous
Goldstone (Brown)
Aventurine glass
mineraloid (man-made)
Opalite
Synthetic glass (SiO2 + metal additions)
mineraloid
Ferruginous Slag (Iron Smelting Byproduct)
Fused Silicate Scoria (Amorphous mixture of FeO, SiO2, and CaO)
Antropogenic Glass / Mineraloid
Geode with Quartz and possibly Jasper/Hematite
Quartz (SiO2) and Chalcedony (cryptocrystalline SiO2), possibly stained by iron oxides
Mineral/Sedimentary Geode
Green Agate
Silicon dioxide (SiO₂)
mineral
Rose Quartz
Silicon Dioxide (SiO2)
mineral
Obsidian
Volcanic glass (no mineral formula due to amorphous structure, mostly SiO2)
igneous
Polished black stone, likely black obsidian
Obsidian (volcanic glass), chiefly silica-rich rhyolitic composition
igneous
Pumice
Pumice; highly vesicular volcanic glass, commonly rhyolitic to dacitic in composition
igneous
Jasper
Microcrystalline Quartz (SiO2)
sedimentary
Chert
Cryptocrystalline quartz (SiO2)
sedimentary
River Pebble
Lithified clastic sediment
sedimentary
Green Sheen Obsidian
Volcanic Glass (SiO2 with microscopic inclusions)
igneous
Black obsidian arrowhead
Obsidian (volcanic glass), primarily silica-rich rhyolitic composition
igneous
Fossiliferous Sedimentary Rock
Sedimentary Rock with Invertebrate Fossil Imprint
fossil
Fulgurite
Fulgurite (Lechatelierite/Silica glass)
mineral
Amber
Fossilized tree resin
gemstone
Septarian Nodule
Septarian Concretion (Calcite, Aragonite, and Limestone)
sedimentary
Limonite / Iron Oxide Concretion
Hydrated iron(III) oxide-hydroxide, FeO(OH)·nH2O
mineral
Limonite
FeO(OH)•nH2O
mineral