Polished fossil coral
Fossilized coral, commonly agatized coral (silica replacing CaCO₃)
fossil
Category
Sedimentary Or Metamorphic (Base Substrate)
Browse sedimentary or metamorphic (base substrate) specimens identified by the Rock Identifier community.
Learn about Sedimentary Or Metamorphic (Base Substrate) in the encyclopedia
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Yellow Apatite
Fluorapatite (Ca5(PO4)3(F,Cl,OH))
mineral
Red Shale
Lutite (primarily composed of clay minerals and iron oxides like hematite, Fe2O3)
sedimentary
Cordierite (Iolite) in Quartz
Cordierite (Magnesium iron aluminium cyclosilicate) - Mg2Al4Si5O18
metamorphic
Quartz Vein in Pelite (Metamorphic Rock)
Hydrothermal Quartz Veining in Metasedimentary Rock (SiO2)
metamorphic
Oak-grain Laminate (Industrial/Decorative Furniture Finish)
Melamine Resin-impregnated Decorative Paper on Particleboard (Cellulose/Thermosetting Plastic)
not a rock (synthetic material)
Quartz
Silicon Dioxide (SiO2)
mineral
Gneiss
Metamorphic Gneiss
metamorphic
Quartzite Pebble
Quartzite (SiO2 based)
metamorphic
Quartz with Iron Staining
SiO2 with Fe oxide impurities
mineral
Aura Quartz Bead
Silicon dioxide (SiO2) with metal coating
mineral with artificial coating
Mica
Mica group (often Muscovite or Biotite)
mineral
Basalt River Pebble
Aphanitic mafic volcanic rock
igneous
Basalt (Beach Pebble)
Basalt (Aphanitic Mafic Igneous Rock)
igneous
Aragonite Star Cluster
Aragonite (Calcium Carbonate - CaCO3)
mineral
Agate
Silicon Dioxide (Chalcedony), SiO2
sedimentary
Navajo Sandstone
Quartz arenite, predominantly SiO₂ (quartz) with iron-oxide cement
sedimentary
Laterite
Laterite (Iron/Aluminum-rich oxide)
sedimentary
Smooth river pebble
Indeterminate lithology; likely fine-grained quartz-rich sandstone, siltstone, or weathered chert
sedimentary
Tiger's Eye
Silicon dioxide (SiO2) - Pseudomorph after crocidolite
mineral
Agate
Chalcedony (SiO2)
sedimentary
Small brown mineral fragment
Unidentified; the image lacks enough detail for a reliable species-level identification
mineral
Banded Gneiss
Metamorphic Gneiss
metamorphic
Anthracite Coal
Anthracite (Carbon based)
metamorphic
Silicified oyster fossil
Fossil oyster shell, commonly Ostrea or Crassostrea, replaced or encrusted by chalcedony/quartz
fossil
Painted River Rock
Artificially Coated Sedimentary Rock
sedimentary
Gravel (Crushed Stone Aggregates)
Mixed Siliciclastic / Carbonate Aggregate
sedimentary
Agate
SiO2 (Chalcedony/Quartz)
sedimentary
Pyrite-bearing rock (likely pyrite-rich schist or sulfide ore)
Pyrite (FeS₂) in a fine-grained host rock; exact host cannot be determined from the image
metamorphic
Likely pyrite-bearing rock
Pyrite (FeS₂), possibly in a quartz- or sulfide-rich matrix
mineral
Graphite
Graphite (Carbon, C)
mineral
Quartzite (or Chert/Flint gravel)
Quartzite (SiO2 with iron oxide inclusions)
metamorphic
Mica (Muscovite or Biotite)
Sheet silicate mineral group (e.g., KAl2(AlSi3O10)(F,OH)2)
mineral
Unidentified gray-brown stone
Likely fine-grained quartz–feldspar rock; exact identification is not possible from this close, blurred image
mineral
Quartz-bearing granite or pegmatite fragment
Likely granitic material composed mainly of quartz (SiO₂), feldspar, and possibly biotite or hornblende
igneous
Mossy Rock
Mixed lithology rock with Bryophyta (moss)
sedimentary
Muscovite
KAl2(AlSi3O10)(OH)2
mineral
Jasper
Silicon dioxide (SiO2) with impurities
sedimentary
Chalcedony (Tumbled Pebble)
Silicon Dioxide (SiO2)
mineral
Gneiss
Gneiss (Metamorphic Rock)
metamorphic
Pumice
Highly vesicular volcanic glass, commonly rhyolitic or andesitic in composition
igneous
Basalt River Stone
Basalt (Mafic volcanic rock)
igneous