Anthracite Coal
Anthracite (high-rank coal / Carbon)
metamorphic
Category
Sedimentary (Fossil)
Browse sedimentary (fossil) specimens identified by the Rock Identifier community.
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Quartz (chalcedony variety) or Limestone with Quartz Veins
SiO2 (for Quartz/Chalcedony); CaCO3 (for Limestone)
Mineral or Sedimentary Rock (with mineral inclusions)
Amber
Fossilized Tree Resin
gemstone
Amber (Rough)
Amber (Fossilized Tree Resin, succinite)
mineral
Amber
Succinicum (Organic polymer, largely C10H16O)
Organic Mineral
Sandstone
Sandstone (Clastic Sedimentary Rock)
Sedimentary Rock
Small rounded pebble, likely quartz-rich stone
Indeterminate from photograph; possibly microcrystalline quartz (SiO₂) or a weathered silicate pebble
mineral
Slate
Foliated low-grade metamorphic rock
metamorphic
Glaucophane-bearing Schist (Blueschist)
Blueschist (Glaucophane-Lawsonite Schist)
metamorphic
Quartzite with Vugs
Metamorphosed Quartz Sandstone (SiO2)
metamorphic
Opal
Hydrous silicon dioxide (SiO2·nH2O)
mineral
Greenschist (or Serpentinite with Manganese Dendrites)
Greenschist facies metamorphic rock
metamorphic
Amber
Succinite (Formula: C10H16O)
Organic Mineraloid
Granite
Phaneritic Igneous Rock (Granoid)
igneous
Vesicular volcanic rock, likely weathered scoria
Scoria (vesicular basaltic-andesitic volcanic rock), composition approximately plagioclase, pyroxene, and volcanic glass
igneous
Crystalline limestone (marble-like calcite rock)
Calcite, CaCO₃; likely recrystallized limestone (marble)
metamorphic
Polished orbicular jasper
Orbicular jasper; microcrystalline quartz (SiO₂) with iron oxides and altered volcanic minerals
metamorphic
Amber
(C10H16O)n – an amorphous organic substance, primarily composed of polymerized isoprenoids.
Mineral
Basalt
Basalt (Mafic Extrusive Igneous Rock)
igneous
Sandstone
Sandstone (composed primarily of sand-sized minerals or rock grains)
sedimentary
River Cobble (likely Metasedimentary)
Metasedimentary Rock / Quartz-rich Sandstone
metamorphic
Petrified Wood
Silicified Wood (SiO2)
metamorphic
Sandstone
Sandstone (arenite is a more specific geological term for a clean sandstone, while wacke refers to a dirty sandstone with significant matrix)
Sedimentary
Slate
Slate (Foliated metamorphic rock)
metamorphic
Pyrite
Pyrite (Iron sulfide, FeS₂)
mineral
Ammolite
Biogenic gemstone (Aragonite, CaCO3)
mineral
Glacial Cobbles (predominantly Granite and Gneiss)
Mixed lithologies (Quartz, Feldspar, Mica assemblage)
igneous and metamorphic
Coal (most likely Bituminous or Anthracite)
Bituminous Coal (Grade of Coal), Anthracite (Grade of Coal)
Sedimentary Rock
Petrified Wood
Silicified Wood (SiO2 - primarily Quartz/Chalcedony/Opal)
Mineral/Fossil (Sedimentary context)
Amber (Black)
Amber (succinite, retinite, etc., specifically, heavily included/dark varieties)
Mineraloid
Ammolite
Ammolite (Biogenic Aragonite with trace elements; fossils of Placenticeras meeki and Placenticeras intercalare)
mineral
Quartz pebble
Silicon dioxide (SiO2)
sedimentary
Generic Pebble / Rock Fragment
Lithic fragment / Weathered rock
sedimentary
Tumbled amber-like chalcedony or resinous fossil material
Likely chalcedony (microcrystalline SiO₂), though the appearance could also indicate copal/amber
gemstone
Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
sedimentary
Banded Siltstone / Mudstone Pebble
Siltstone / Argillite
sedimentary
Shale fragment
Shale (clay mineral rich sedimentary rock)
sedimentary
Shale / Mudstone
Sedimentary rock (Claystone / Mudstone / Shale)
sedimentary
Brown Sandstone (River Rock)
Arenite
sedimentary
Shale
Sedimentary Shale
sedimentary
Shale and Pebble Fragment
Sedimentary Rock (Mudstone/Shale with Silica Pebble)
sedimentary
Sandstone (with Iron Staining)
Clastic sedimentary rock (primarily SiO2 with Fe2O3)
sedimentary