Blue Sapphire
Corundum (Al2O3 with trace Titanium and Iron)
mineral
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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Gravel / Small Pebble
Rock Fragment (Gravel)
sedimentary
Zoisite with Ruby
Anyolite (Calcium aluminum hydroxy silicate with Corundum) Ca2Al3(SiO4)3(OH)
metamorphic
Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Quartz River Pebble
Silicon Dioxide (SiO2)
mineral
White Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Red Sandstone (Old Red Sandstone Pebble)
Arenite with iron oxide (Fe2O3) cement
sedimentary
Polished fossil coral
Fossilized coral, commonly agatized coral (silica replacing CaCO₃)
fossil
Banded River Cobble (Argillite or Shale)
Laminated Mudstone / Argillite
sedimentary
River Stone (Chert/Siltstone)
Cryptocrystalline Quartz (SiO2) with trace impurities
sedimentary
Note: Item is a Synthetic/Man-made Object
Titanium-coated Stainless Steel (Fe-Cr-Ni-Ti)
Non-geological
Hand-Drawn Trading Card (Amateur Artwork)
Cellulose-based substrate with wax/graphite/ink deposit (n/a for minerals)
Organic/Synthetic Composite (Paper and Pigment)
Vesicular basalt (scoria-like lava rock)
Mafic volcanic rock, typically plagioclase + pyroxene ± olivine; vesicles formed by trapped volcanic gas
igneous
Quartz Vein in Pelite (Metamorphic Rock)
Hydrothermal Quartz Veining in Metasedimentary Rock (SiO2)
metamorphic
Zoisite with Hornblende
Zoisite (Ca2Al3(SiO4)3(OH)) with Amphibole inclusions
metamorphic
Quartzite with Mica / Gneiss Pebble
Metamorphic Rock (Quartz-Feldspar-Mica aggregate)
metamorphic
Sandstone (River Pebble)
Quartz Arenite / Lithic Sandstone
sedimentary
Mixed tumbled gravel and quartz-rich sandstone
Primarily quartz (SiO₂), feldspar, and lithic sedimentary fragments; one piece appears to be quartz-rich sandstone
sedimentary
Agate
Silicon Dioxide (Chalcedony), SiO2
sedimentary
White Sapphire
Corundum (Al2O3)
mineral
Agate
Chalcedony (SiO2)
sedimentary
Tiger's Eye
Silicon dioxide (SiO2) - Pseudomorph after crocidolite
mineral
Red Jasper
Silicon Dioxide (SiO2) with Hematite (Fe2O3) inclusions
sedimentary
Silicified oyster fossil
Fossil oyster shell, commonly Ostrea or Crassostrea, replaced or encrusted by chalcedony/quartz
fossil
Cordierite (Iolite) in Quartz
Cordierite (Magnesium iron aluminium cyclosilicate) - Mg2Al4Si5O18
metamorphic
Red Shale
Lutite (primarily composed of clay minerals and iron oxides like hematite, Fe2O3)
sedimentary
Agate
SiO2 (Chalcedony/Quartz)
sedimentary
Quartz-bearing granite or pegmatite fragment
Likely granitic material composed mainly of quartz (SiO₂), feldspar, and possibly biotite or hornblende
igneous
Colorless Quartz (Rhinestone)
Silicon Dioxide (SiO2)
mineral
Mossy Rock
Mixed lithology rock with Bryophyta (moss)
sedimentary
Jasper
Silicon dioxide (SiO2) with impurities
sedimentary
Chalcedony (Tumbled Pebble)
Silicon Dioxide (SiO2)
mineral
Unidentified gray-brown stone
Likely fine-grained quartz–feldspar rock; exact identification is not possible from this close, blurred image
mineral
Oak-grain Laminate (Industrial/Decorative Furniture Finish)
Melamine Resin-impregnated Decorative Paper on Particleboard (Cellulose/Thermosetting Plastic)
not a rock (synthetic material)
Gneiss
Gneissic Metamorphic Rock
metamorphic
Smooth river pebble
Indeterminate lithology; likely fine-grained quartz-rich sandstone, siltstone, or weathered chert
sedimentary
Aragonite Star Cluster
Aragonite (Calcium Carbonate - CaCO3)
mineral
Mixed river stones and gravel
Polymictic alluvial clasts; individual pieces may include quartzite, granite, basalt, sandstone, limestone, and slate
igneous, sedimentary, metamorphic
Basalt River Pebble
Aphanitic mafic volcanic rock
igneous
Basalt (Beach Pebble)
Basalt (Aphanitic Mafic Igneous Rock)
igneous
Yellow Apatite
Fluorapatite (Ca5(PO4)3(F,Cl,OH))
mineral
Limonite (Iron Ore)
FeO(OH)·nH2O (Hydrated iron(III) oxide-hydroxide)
mineral