Chalcedony (Agate/Opal hybrid)
Microcrystalline Quartz (SiO2) with potential amorphous silica (SiO2·nH2O)
Category
Browse amorphous solid specimens identified by the Rock Identifier community.
Chalcedony (Agate/Opal hybrid)
Microcrystalline Quartz (SiO2) with potential amorphous silica (SiO2·nH2O)
Pumice (Volcanic Rock)
Vesicular volcanic rock (composed largely of amorphous volcanic glass)
Pumice
Pumicite (Amorphous glass with varying chemical composition, often rhyolitic)
Pumice
Pumice (Volcanic Rock / Glass Foam)
Petrified Wood with Lichen
Silicified Wood (SiO2) colonized by crustose lichens
Amber
Succinite (C10H16O)
Iron Slag
Ferrous Slag (complex silicate and oxide byproduct)
Golden Sheen Obsidian
Obsidian (volcanic glass) with inclusions of gas bubbles and mineral crystals (e.g., hematite, magnetite) causing the sheen
Obsidian (likely mahogany or black obsidian)
Volcanic glass; chiefly amorphous SiO₂-rich rhyolitic composition
Sea Glass
Amorphous silicon dioxide (man-made glass weathered by nature)
Petrified Wood
Silicified Wood (SiO2)
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)
Amygdaloidal Basalt
Extrusive Igneous Rock with Secondary Mineral Fillings
Chrysocolla
Hydrated copper phyllosilicate, (Cu,Al)2H2Si2O5(OH)4·nH2O
Dendritic Agate (or Dendritic Opal)
SiO2 (for Agate), SiO2·nH2O (for Opal)
Bouncy Ball (Synthetic Rubber Polymer)
Polybutadiene / Ethylene Vinyl Acetate (EVA)
Slag
Anthropogenic Vitrification Product / Silicate Slag
Pumice
Pumice (Volcanic Rock)
Obsidian
Obsidian (volcanic glass)
Limonite / Goethite Ironstone Concretion
FeO(OH)·nH2O (Hydrated Iron Oxide)
Pumice
Pumice (Volcanic Glass with Vesicular Texture)
Amber
Fossilized tree resin (not a true mineral as it is organic and amorphous); Chemical formula is highly variable, but often approximated as C10H16O.
Goldfish Cracker (Culinary Mimic)
Cibus aurum (Commonly composed of Enriched Wheat Flour and Cheddar Cheese)
Gossan / Iron Ore Rock
Hematite / Goethite / Limonite iron oxide assemblage
Pearl
Calcium Carbonate (Aragonite or Calcite) and Conchiolin
Chert
Chert (variant of microcrystalline quartz)
Obsidian
Volcanic Glass (predominantly SiO2 – Silicon Dioxide, but non-crystalline)
Pumice
Pumice (a highly vesicular extrusive igneous rock, primarily amorphous silica)
Ironstone Matrix with Jasper / Chert
Ferruginous Chert / Limonitic Jasper (SiO2 with Fe-oxides)
Limonite (Iron Ore/Hydrated Iron Oxide)
Limonite (mixture of FeO(OH)·nH₂O minerals, mainly Goethite, FeO(OH) and Lepidocrocite, FeO(OH))
Ironstone Concretion / Goethite-Hematite Geode
Goethite / Hematite Concretion (Fe3O4 / FeO(OH) / Fe2O3)
Chalk
CaCO3 (primarily Calcium Carbonate), biogenic sedimentary rock
Amber (Black)
Amber (succinite, retinite, etc., specifically, heavily included/dark varieties)
Laterite
Laterite (primarily composed of hydrated oxides of iron and aluminum)
Fossil Coral
Fossilized Scleractinia or Tabulata (various genera/species)
Wood Beads (Palmwood/Ebony)
Various species for wood, but often refers to woods like Palmwood (e.g., Borassus flabellifer) or Ebony (Diospyros spp.) for their distinctive grain and hardness.
Brick
Fired clay or Ceramic material (no specific mineralogical scientific name as it's a composite)
Iron-rich botryoidal limonite/goethite specimen
Limonite (amorphous hydrated iron oxides, chiefly goethite, α-FeO(OH))
Clay (as a rock-forming material)
Clay minerals (e.g., Kaolinite group, Smectite group, Illite group, Chlorite group)
Probable amber fragment
Amber (fossilized plant resin; chiefly amorphous organic resin, commonly dominated by succinite)
Scoria
Scoria (a vesicular basalt or andesite)
Goldstone
N/A (Synthetic Glass with Copper Inclusions)