Quartz (Milky/Gravel variety)
Silicon Dioxide (SiO2)
mineral
Category
Igneous And Sedimentary
Browse igneous and sedimentary specimens identified by the Rock Identifier community.
Dendritic Opal (Common Opal)
Amorphous Hydrated Silica (SiO2·nH2O) with Manganese or Iron Oxide inclusions
mineral
Banded Gneiss
Gneiss (High-grade Regional Metamorphic Rock)
metamorphic
Yellow Chalcedony (Carnelian/Yellow Agate)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
Mineral
Blue-dyed Quartz Druzy
Silicon Dioxide (SiO2) with artificial pigment
mineral
Amethyst
Amethyst (SiO2 - Silicon Dioxide with iron impurities)
mineral
Gneiss
Foliated Metamorphic Rock (Gneiss)
metamorphic
Banded Gneiss
Gneiss (Metamorphic Rock)
metamorphic
Gneiss (specifically a weathered or stream-worn specimen)
Gneiss (Foliated Metamorphic Rock)
metamorphic
Banded Gneiss
Gneiss (Metamorphic high-grade rock)
metamorphic
Quartz Geode Fragment
Silicon Dioxide (SiO2)
mineral
Gneiss
Gneiss (High-grade regional metamorphic rock)
metamorphic
Agate Geode
Chalcedony (SiO2 - Silicon Dioxide)
sedimentary (secondary mineral formation)
River Stone (Basalt or Siltstone with banding)
Polished Basaltic or Siliciclastic River Cobble
igneous or sedimentary
River Cobble (Gneiss/Migmatite)
Gneissic Metamorphic Rock (composed mainly of Quartz, Feldspar, and Biotite)
metamorphic
Gneiss
Gneiss (High-grade metamorphic rock typically composed of Quartz, Feldspar, and Mica/Amphibole)
metamorphic
River Rocks (Basalt and Sedimentary Stones)
Mafic Igneous Rock (Basalt) and Clastic Sedimentary Rock
igneous and sedimentary
Pyrite
Pyrite (FeS₂)
Mineral
Chalcedony (or a variety of Chalcedony, likely Agate or Jasper)
Chalcedony (SiO₂)
Mineral (or mineraloid if microcrystalline)
Banded River Cobble with Mafic Dike
Hydrothermally altered Graywacke or Sandstone with Mafic Intrusion
igneous and sedimentary
Pebble (Likely Basalt or Siltstone)
Clastic sedimentary rock or mafic volcanic rock
Igneous or Sedimentary
Wishing Stone (Basalt or Mudstone with Quartz/Calcite Veins)
Hydrothermally veined Basalt (SiO2/CaCO3 intrusions)
igneous or sedimentary
Pink Opal / Peruvian Opal
Hydrated amorphous silicon dioxide (SiO2·nH2O)
Mineral
Ruby in Zoisite
Ruby (α-Al2O3) embedded in Zoisite (Ca2Al3(SiO4)3(OH)) with some Hornblende
Metamorphic Rock (composed of multiple minerals)
Wishing Stone (Basalt or Siltstone with Quartz/Calcite Vein)
Basalt (SiO2+MgO+FeO) or Siltstone with a Quartz (SiO2) or Calcite (CaCO3) vein
igneous or sedimentary
Granite (phaneritic background) with Limestone/Calcite carving
Felsic Igneous Plutonic Rock (background) / Calcium Carbonate (CaCO3) (carving)
igneous and sedimentary
River Pebbles (Tumbled Quartz and Basalt)
Silicon Dioxide (SiO2) for white quartz; Mafic Volcanic Rock for basalt
igneous and sedimentary
River Rock (Basalt/Greywacke pebbles)
Fluvial gravel primarily composed of Mafic Volcanic Rock (Basalt) or Lithic Sandstone (Greywacke)
igneous and sedimentary
Epidote in Quartz
Quartz with Epidote inclusions (SiO2 with Ca2(Al,Fe)3(SiO4)3(OH) inclusions)
Mineral
Banded Rock (likely Quartz-rich)
Uncertain, likely a Metamorphic Rock (e.g., Gneiss or Schist) with prominent Quartz and other minerals
Mineral
Garnet (Red Garnet)
Garnet Group. The red varieties seen in jewelry are typically Almandine (Fe3Al2(SiO4)3), Pyrope (Mg3Al2(SiO4)3), or a mix of the two (pyrope-almandine series).
Mineral (specifically, a variety of the mineral species Pyrope-Almandine Garnet)
Apatite
Apatite group mineral (e.g., Fluorapatite - Ca5(PO4)3F, Chlorapatite - Ca5(PO4)3Cl, Hydroxylapatite - Ca5(PO4)3(OH))
mineral
Carnelian
Chalcedony (cryptocrystalline quartz), SiO2
Mineral
Banded Gneiss
Gneiss (variable mineral composition)
metamorphic
Quartz / Limestone Gravel
SiO2 (Silicon Dioxide) and CaCO3 (Calcium Carbonate)
igneous and sedimentary mixture
Epidote (or Epidote-rich rock)
Epidote. Mineral formula: Ca2(Al,Fe)3(SiO4)3(OH).
Mineral, often found in metamorphic rocks but also in sedimentary and igneous rocks
Banded River Rock / Gneiss (highly weathered)
Gneiss
Metamorphic rock
Red Chalcedony (likely dyed)
Chalcedony (a variety of Quartz), SiO2
Mineral (Cryptocrystalline Quartz)
Obsidian and Green Calcite
Volcanic Glass and Calcium Carbonate (CaCO3)
igneous and sedimentary/mineral
Banded Gneiss
Gneiss (pronounced "nice")
metamorphic
Gneiss
Gneiss (a type of metamorphic rock)
Metamorphic Rock
River Cobbles (Basalt, Quartzite, and Sandstone mix)
Fluvial detritus (primarily SiO2, Plagioclase, and Pyroxene mix)
Mixed: Igneous and Sedimentary