Igneous Rock

Browse igneous rock specimens identified by the Rock Identifier community.

Desert Rose (Baryte or Selenite variant)

Barium Sulfate (BaSO4) or Gypsum (CaSO4·2H2O) with Sand inclusions

mineral

River Rock / Stream Pebble

Fluvial Clast / Rounded Sedimentary Particle

Sedimentary Rock (possibly composed of various minerals)

Banded Gneiss (with possible weathered sulfide or iron staining)

Gneiss, potentially with iron oxide/hydroxide staining (e.g., limonite) or weathered sulfides

Metamorphic

Quartz

Quartz (SiO₂)

Mineral

Amazonite

KAlSi3O8 (Potassium Aluminum Silicate) - a variety of Microcline Feldspar

mineral

Sandstone

Clastic sedimentary rock (primarily SiO2)

sedimentary

Yellow Quartzite (River Pebble)

Quartzite (SiO2)

metamorphic

Geode with Quartz and possibly Jasper/Hematite

Quartz (SiO2) and Chalcedony (cryptocrystalline SiO2), possibly stained by iron oxides

Mineral/Sedimentary Geode

Pyrite

Pyrite (Iron Disulfide), FeS2

Mineral

Crushed Stone (Gravel/Aggregates)

Crushed rock aggregate (varied composition including Granite, Limestone, and Quartz)

sedimentary and igneous (mixed)

Sapphire

Corundum (Al₂O₃) with trace elements causing color variations.

Mineral

Quartz Geode

Silicon Dioxide (SiO2)

mineral

Druzy Quartz on Chert/Chalcedony

Silicon Dioxide (SiO2)

mineral

Quartz

Quartz (Silicon Dioxide - SiO2)

Mineral

Quartz Geode (likely within Limestone or Dolomite matrix)

Quartz (SiO₂)

Mineral within a Sedimentary Rock

River Cobble (Gneiss/Migmatite)

Gneissic Metamorphic Rock (composed mainly of Quartz, Feldspar, and Biotite)

metamorphic

Banded Gneiss

Gneiss (High-grade metamorphic rock typically composed of Quartz, Feldspar, and Mica)

metamorphic

Smoky Quartz

Smoky Quartz (SiO ₂)

Mineral

Mixed Tumbled Gemstones and River Rocks

Mixed Decorative Stones (predominantly Silicon Dioxide - SiO2 variants)

Mixed (Igneous, Sedimentary, Metamorphic, and Minerals)

Quartz Vein in Host Rock

Silicon Dioxide (SiO2) within Sedimentary/Metamorphic Matrix

Metamorphic or Igneous (context dependent)

Rutilated Quartz

Quartz (SiO2) with Rutile (TiO2) inclusions

Mineral

Quartz (Float/Abraded)

Quartz (SiO₂)

Mineral

Amber-bearing Coal/Sedimentary Rock

Bituminous coal or carbonaceous siltstone with Fossilized Tree Resin (C10H16O)

sedimentary

Shale (Beach-worn)

Laminated Pelite (primarily clay minerals and quartz)

sedimentary

Quartzite (Yellow/Orange variety)

Quartzite (primarily SiO2)

metamorphic

Desert Varnish on Sandstone

Ferromanganese coating on Quartz Arenite

sedimentary

Prehnite

Prehnite, Ca2Al2Si3O10(OH)2

Mineral

Muscovite Mica

Muscovite (Potassium Mica) KAl2(AlSi3O10)(OH)2

Mineral

Granite (phaneritic background) with Limestone/Calcite carving

Felsic Igneous Plutonic Rock (background) / Calcium Carbonate (CaCO3) (carving)

igneous and sedimentary

Fluorite and Rose Quartz

Fluorite (CaF2), Rose Quartz (SiO2)

Mineral

Granite (Alkali-feldspar Granite)

Felsic Plutonic Rock (Primary minerals: Quartz SiO2, Orthoclase KAlSi3O8, Plagioclase (Na,Ca)AlSi3O8)

igneous

Epidote

Epidote Group (e.g., Clinozoisite, Epidote, Piemontite), Epidote formula: Ca2(Al,Fe)3(SiO4)3(OH)

Mineral

Quartz

Silicon dioxide (SiO2)

Mineral

Garnet (likely Pyrope or Almandine)

Garnet Group (complex nesosilicate minerals, e.g., Pyrope Mg3Al2(SiO4)3, Almandine Fe3Al2(SiO4)3, Spessartine Mn3Al2(SiO4)3, Grossular Ca3Al2(SiO4)3, Andradite Ca3Fe2(SiO4)3, Uvarovite Ca3Cr2(SiO4)3). The vivid red color in the image strongly suggests Pyrope or Almandine.

Mineral