Gneiss
Gneiss (High-grade regional metamorphic rock)
Category
Browse igneous and mineral specimens identified by the Rock Identifier community.
Gneiss
Gneiss (High-grade regional metamorphic rock)
Gneiss (Metamorphic Rock)
Gneiss
Dragon Stone (Dragon Blood Jasper)
Epidote with Pietersite or Red Jasper inclusions (varied SiO2 and Ca2(Al,Fe)3(SiO4)3(OH))
Gneiss (with Quartz and Biotite Mica)
Gneiss
Pebble (likely Quartz or Chert)
SiO₂ (Silicon Dioxide) - referring to the likely main mineral composition, Quartz. If it's chert, the scientific name remains SiO₂ with a microcrystalline structure.
Amethyst
Silicon Dioxide (SiO2) with iron impurities
Amethyst
Amethyst (Silicon Dioxide, SiO2 with Iron impurities)
Schist (Chlorite or Mica-rich)
Chlorite Schist
Greenschist
Greenschist (Actinolite-Chlorite Schist)
Amazonite
Amazonite (KAlSi3O8 – a variety of Microcline, a Potassium Feldspar)
Amethyst
SiO2 (Silicon Dioxide with Iron impurities)
Iolite (Cordierite)
Cordierite (Magnesium Aluminum Silicate), Mg2Al4Si5O18
Garnet (likely Almandine)
Almandine (Fe3Al2(SiO4)3)
Granite
Granite (composed primarily of Quartz SiO2, Alkali Feldspar KAlSi3O8, and Plagioclase Feldspar)
Quartz (River Pebble)
Silicon Dioxide (SiO2)
Vesicular Basalt (Amygdaloidal)
Vesicular Basalt (Fe-Mg rich extrusive volcanic rock)
Basalt
Basalt (Aphanitic Mafic Volcanic Rock)
Basalt with Olivine Phenocrysts
Porphyritic Basalt (Mineral formula of Olivine: (Mg,Fe)2SiO4)
Quartz (Milky or White Quartz)
Silicon Dioxide (SiO2)
Quartz (Vein Quartz)
Silicon Dioxide (SiO2)
Quartz (Milky Quartz)
Silicon Dioxide (SiO2)
Mahogany Obsidian
Volcanic Glass with Hematite/Magnetite inclusions
Porphyritic Basalt (with Pyrolusite or Iron-oxide staining)
Porphyritic Basalt (Mafic Extrusive)
Black Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
Vesicular Basalt
Vesicular Basalt (Aphanitic Mafic Rock)
Pyrite
Iron Sulfide (FeS2)
Biotite (Black Mica)
Biotite (K(Mg,Fe)3AlSi3O10(OH)2)
Obsidian
Obsidian (principally SiO2 with MgO and Fe3O4)
Wonderstone
Rhyolite (Silicon Dioxide with Iron Oxide impurities)
Gneiss
Gneiss (High-grade Metamorphic Rock)
Diorite
Diorite
Diorite (Gneissic)
Diorite
Quartz Pebble (Iron-stained)
Silicon Dioxide (SiO2)
Basalt Pebble with Epidote/Olivine
Vitreous Basalt (SiO2 with Ca/Mg/Fe silicates)
Milky Quartz
Silicon Dioxide (SiO2)
Amethyst
Silicon Dioxide (SiO2) with iron impurities
Granite
Granite (Felsic Plutonic Rock)
Pink Granite
Phaneritic Plutonic Felsic Rock (K-feldspar rich)
Granite
Granite (Felsic Plutonic Rock)
Fluorite in Matrix
Fluorite (CaF2) within a host rock matrix
Amazonite (Amazon Stone)
Tectosilicate Microcline (KAlSi3O8)
Sandstone (Ferruginous)
Arenite (primarily SiO2 with Fe2O3 inclusions)