Rock Identifier

Category

Crystal

Browse crystal specimens identified by the Rock Identifier community.

Milky Quartz (Quartz (Silicon Dioxide, SiO2)) — mineral

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

White Quartz (Milky Quartz Pebble) (Silicon Dioxide (SiO2)) — mineral

White Quartz (Milky Quartz Pebble)

Silicon Dioxide (SiO2)

Chert Geode with Quartz Druzy (Microcrystalline Quartz (SiO2) with macrocrystalline Quartz) — sedimentary

Chert Geode with Quartz Druzy

Microcrystalline Quartz (SiO2) with macrocrystalline Quartz

Chert (Nodule) (Silicon Dioxide (SiO2)) — sedimentary

Chert (Nodule)

Silicon Dioxide (SiO2)

Chalcedony Nodule (Agate/Chert) (Chalcedony (cryptocrystalline Silicon Dioxide, SiO2)) — mineral

Chalcedony Nodule (Agate/Chert)

Chalcedony (cryptocrystalline Silicon Dioxide, SiO2)

Magnetite (Magnetite (Fe3O4)) — Mineral

Magnetite

Magnetite (Fe3O4)

Granite (Phaneritic Felsic Igneous Rock) — igneous

Granite

Phaneritic Felsic Igneous Rock

Quartz (Water-worn pebble) (Silicon Dioxide (SiO2)) — mineral

Quartz (Water-worn pebble)

Silicon Dioxide (SiO2)

Botryoidal Chalcedony (Agate/Desert Rose Chalcedony) (Silicon Dioxide (SiO2) - Cryptocrystalline Quartz) — mineral

Botryoidal Chalcedony (Agate/Desert Rose Chalcedony)

Silicon Dioxide (SiO2) - Cryptocrystalline Quartz

Quartz with Iron Staining (Silicon Dioxide (SiO2)) — mineral

Quartz with Iron Staining

Silicon Dioxide (SiO2)

Quartz Pebble (Water-worn) (Silicon Dioxide (SiO2)) — mineral

Quartz Pebble (Water-worn)

Silicon Dioxide (SiO2)

Opalite (Synthetic Glass (Simulated Opal)) — mineral

Opalite

Synthetic Glass (Simulated Opal)

Geode (unopened) (Chert / Chalcedony Geode (SiO2)) — sedimentary

Geode (unopened)

Chert / Chalcedony Geode (SiO2)

Quartz Vein in River Siltstone (Crystalline Quartz (SiO2) in Siliclastic Matrix) — sedimentary

Quartz Vein in River Siltstone

Crystalline Quartz (SiO2) in Siliclastic Matrix

Concretion (Septarian concretion (likely containing Calcite or Siderite)) — sedimentary

Concretion

Septarian concretion (likely containing Calcite or Siderite)

Porphyry (specifically Porphyritic Rhyolite or Andesite) (Porphyritic Igneous Rock (composed of Phenocrysts in an Aphanitic groundmass)) — igneous

Porphyry (specifically Porphyritic Rhyolite or Andesite)

Porphyritic Igneous Rock (composed of Phenocrysts in an Aphanitic groundmass)

Basalt (Mafic Volcanic Rock (composed of Plagioclase Feldspar and Pyroxene)) — igneous

Basalt

Mafic Volcanic Rock (composed of Plagioclase Feldspar and Pyroxene)

Diorite (or salt-and-pepper granite pebble) (Phaneritic Igneous Rock (Intermediate Composition)) — igneous

Diorite (or salt-and-pepper granite pebble)

Phaneritic Igneous Rock (Intermediate Composition)

Granite (Phaneritic Intrusive Igneous Rock (primarily Quartz, Feldspar, and Mica)) — igneous

Granite

Phaneritic Intrusive Igneous Rock (primarily Quartz, Feldspar, and Mica)

Sunstone with Black Tourmaline (Arfvedsonite) (Feldspar (Na,Ca)(Al,Si)4O8 with Schorl Na(Fe3+)3Al6(Si6O18)(BO3)3(OH)3(OH)) — mineral

Sunstone with Black Tourmaline (Arfvedsonite)

Feldspar (Na,Ca)(Al,Si)4O8 with Schorl Na(Fe3+)3Al6(Si6O18)(BO3)3(OH)3(OH)

Blue Kyanite (Kyanite (Al2SiO5)) — mineral

Blue Kyanite

Kyanite (Al2SiO5)

Howlite (Calcium borosilicate hydroxide (Ca2B5SiO9(OH)5)) — mineral

Howlite

Calcium borosilicate hydroxide (Ca2B5SiO9(OH)5)

Limonite Pseudomorph after Pyrite (Limonite (Hydrous iron oxides e.g., FeO(OH)·nH2O) pseudomorphing Pyrite (FeS2)) — mineral

Limonite Pseudomorph after Pyrite

Limonite (Hydrous iron oxides e.g., FeO(OH)·nH2O) pseudomorphing Pyrite (FeS2)

Yellow Quartzite (Quartzite (primarily SiO2)) — metamorphic

Yellow Quartzite

Quartzite (primarily SiO2)

Milky Quartz with Mineral Inclusions (Silicon Dioxide (SiO2)) — mineral

Milky Quartz with Mineral Inclusions

Silicon Dioxide (SiO2)

Granite (Granite) — igneous

Granite

Granite

Phyllite (Phyllite) — metamorphic

Phyllite

Phyllite

Obsidian (worked into an arrowhead profile)

Obsidian (volcanic glass), primarily SiO2 (Silicon Dioxide)

Obsidian (Apache Tear) (Obsidian / Amorphous Volcanic Glass (main component: SiO2)) — igneous

Obsidian (Apache Tear)

Obsidian / Amorphous Volcanic Glass (main component: SiO2)

Milky Quartz (Silicon Dioxide (SiO2)) — mineral

Milky Quartz

Silicon Dioxide (SiO2)

Obsidian (Obsidian (principally SiO2)) — igneous

Obsidian

Obsidian (principally SiO2)

Granite (Phaneritic Felsic Igneous Rock (composed of SiO2, KAlSi3O8, NaAlSi3O8)) — igneous

Granite

Phaneritic Felsic Igneous Rock (composed of SiO2, KAlSi3O8, NaAlSi3O8)

Obsidian / Chert (Arrowhead Artifact) (Obsidian (volcanic glass, SiO2 with impurities)) — igneous

Obsidian / Chert (Arrowhead Artifact)

Obsidian (volcanic glass, SiO2 with impurities)

Obsidian Arrowhead (Volcanic Glass (70% or more SiO2)) — Igneous

Obsidian Arrowhead

Volcanic Glass (70% or more SiO2)

Obsidian (Volcanic Glass (Primary composition: SiO2 - Silicon Dioxide)) — igneous

Obsidian

Volcanic Glass (Primary composition: SiO2 - Silicon Dioxide)

Obsidian (Volcanic Glass (SiO2 - Silicon Dioxide with impurities)) — igneous

Obsidian

Volcanic Glass (SiO2 - Silicon Dioxide with impurities)

Obsidian (Volcanic glass (SiO2 - Silicon Dioxide)) — igneous

Obsidian

Volcanic glass (SiO2 - Silicon Dioxide)

Obsidian Arrowhead (Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)) — igneous

Obsidian Arrowhead

Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)

Milky Quartz (Quartz (Silicon Dioxide, SiO2)) — mineral

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Basalt (Mafic Volcanic Rock (composed mainly of Plagioclase, Pyroxene, and Olivine)) — igneous

Basalt

Mafic Volcanic Rock (composed mainly of Plagioclase, Pyroxene, and Olivine)

Basalt (Extrusive mafic igneous rock) — igneous

Basalt

Extrusive mafic igneous rock

Biotite (Black Mica) (Biotite - K(Mg,Fe)3AlSi3O10(F,OH)2) — mineral

Biotite (Black Mica)

Biotite - K(Mg,Fe)3AlSi3O10(F,OH)2