Obsidian
Amorphous volcanic glass (primarily SiO2)
igneous
Category
Amorphous Solid
Browse amorphous solid specimens identified by the Rock Identifier community.
Cullet Glass (Slag Glass)
Amorphous Silicon Dioxide (Industrial Byproduct)
mineraloid
Green Slag Glass
Cullet (Amorphous Silicon Dioxide with impurities)
Man-made rock-like material
Obsidian
Volcanic Glass (Amorphous Silicon Dioxide)
igneous
Snowflake Obsidian
Volcanic Glass with Spherulitic Cristobalite (SiO2)
igneous
Lignite (Brown Coal)
Lignite (C189H155O6N3S)
sedimentary
Coquina (Limestone)
Bioclastic Limestone (CaCO3)
sedimentary
Mixed Gemstone Collection
SiO2 (Quartz varieties) and Biogenic CaCO3 (Nacre)
mineral
Porcelain (White Ceramic)
Mullite-bearing Vitrified Ceramic (Major phases: Mullite Al6Si2O13, Glassy Silica SiO2)
metamorphic
Amber / Copal
Succinite (fossilized tree resin)
mineraloid
Baroque Pearl
Biogenic Calcium Carbonate (Aragonite/Conchiolin)
mineral
ABS Plastic (Acrylonitrile Butadiene Styrene)
(C8H8)x·(C4H6)y·(C3H3N)z
Synthetic Polymer (Synthetic Material)
Brachiopod Fossil
Phylum Brachiopoda (likely Order Rhynchonellida or Spiriferida)
sedimentary
Amber
Succinite
Organic Mineral
Amber
Amber (C10H16O)
mineral
Shungite
Non-crystalline carbon (allotrope of carbon)
metamorphic
Sandstone (with possibly iron oxides and other minerals)
Sandstone
Sedimentary rock
Sandstone
Sandstone (arenite is a more specific geological term for a clean sandstone, while wacke refers to a dirty sandstone with significant matrix)
Sedimentary
Snowflake Obsidian
Obsidian (volcanic glass) with Cristobalite inclusions
igneous
Sea Glass (often mistaken for Gemstones)
Amorphous Silica (SiO2) with trace additives
mineraloid
Snowflake Obsidian
Volcanic glass (SiO2) with Cristobalite (SiO2) inclusions
igneous
Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
igneous
Chalk
Calcium Carbonate (CaCO3)
sedimentary
Amber
Succinite (Organic Gemstone)
mineral
Mahogany Obsidian
Volcanic Glass with Hematite/Magnetite inclusions (SiO2 + Fe2O3)
igneous
Amber
Succinite (approximate formula C10H16O)
mineral
Amber with Inclusion
Succiniferous fossil resin (C10H16O)
mineraloid
Portable Ceramic Space Heater
Polished Acrylonitrile Butadiene Styrene (ABS) Plastic with Ceramic Heating Elements
not a rock (synthetic/industrial object)
Amber
Succinite (C10H16O)
mineral
Amber in Matrix
Succinite (Carbon-based organic polymer)
Organic (Sedimentary context)
Limonite (Ironstone)
Hydrated Iron Oxide (FeO(OH)·nH2O)
mineral
Man-made Synthetic Material (Plastic/Composite)
Acrylonitrile Butadiene Styrene (ABS) or High-Impact Polystyrene (HIPS)
Non-geological / Synthetic
Apache Tear (Obsidian)
Obsidian / Amorphous Volcanic Glass (primarily SiO2)
igneous
Pink Opal
Hydrated Amorphous Silica (SiO2·nH2O)
Mineral
Black Opal
Hydrated Amorphous Silica (SiO2·nH2O)
Mineral
Glass Nugget (Tumbled Glass)
Amorphous Silicon Dioxide (SiO2) with additives
mineraloid (man-made)
Mahogany Obsidian
Volcanic Glass with Hematite/Magnetite inclusions (SiO2 + Fe2O3)
Igneous
Cobalt Glass Slug (Man-made Glass)
Amorphous Silica with Cobalt Oxide (SiO2 + CoO)
mineraloid
Sea Glass (Teal/Turquoise)
Amorphous Silica (SiO2) with trace metal oxides
Anthropogenic (Man-made material processed by nature)
Graveler (Fictional Interpretation)
Mons calcarius anthropomorphus
igneous
Limonite (Iron Ore)
Limonite (FeO(OH)·nH2O)
mineral
Conch Pearl
Calcareous concretion (CaCO3)
mineraloid