Gneiss
Gneiss
Category
Browse igneous rock specimens identified by the Rock Identifier community.
Gneiss
Gneiss
Milky Quartz Pebble
Quartz (Silicon Dioxide, SiO2)
Hypersthene (or Enstatite/Ferrosilite)
Orthopyroxene series (Mg,Fe)SiO3 - specifically, historically hypersthene (intermediate member) now referred to as Enstatite (Mg-rich) or Ferrosilite (Fe-rich)
Gold Ore
Native Gold (Au) in Matrix
Milky Quartz
Silicon Dioxide (SiO2)
Milky Quartz (with Iron Oxide staining)
Silicon Dioxide (SiO2)
Gneiss
Gneiss (High-grade metamorphic rock)
Granitic Gneiss
Gneiss (containing Potassium Feldspar and Quartz)
Basalt
Basalt (Mafic volcanic rock, primarily Plagioclase and Pyroxene)
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
Basalt with Olivine Phenocrysts
Porphyritic Basalt (Mineral formula of Olivine: (Mg,Fe)2SiO4)
Pumice
Pumice (Vesicular Rhyolite/Dacite)
Basalt with Phenocrysts (Porphyritic Basalt)
Porphyritic Basalt (primarily Plagioclase and Pyroxene)
Basalt
Aphanitic mafic volcanic rock (primarily plagioclase feldspar and pyroxene)
Snowflake Obsidian
Volcanic glass containing Cristobalite (SiO2)
Pink Granite
Granite (rich in Potassium Feldspar/Orthoclase)
Vesicular Basalt (commonly mistaken for Slag)
Scoriaceous Basalt (composed primarily of Plagioclase Feldspar and Pyroxene)
Pumice
Pumice (a highly vesicular, silicic volcanic rock)
Granite
Phaneritic plutonic rock (primarily Quartz, Feldspar, and Mica)
Basalt
Mafic Volcanic Basalt (Major minerals: Plagioclase feldspar, Pyroxene; Minor: Olivine, Magnetite)
Pumice
Pumice (Amorphous volcanic glass)
Amygdaloidal Basalt
Amygdaloidal Basalt
Obsidian
Volcanic Glass (Amorphous Silicon Dioxide)
Sandstone (Red)
Arenite (primarily Quartz, SiO2, with Iron Oxide cement)
White Quartz Pebble
Quartz (Silicon Dioxide, SiO2)
Clear Quartz (Rock Crystal)
Silicon Dioxide (SiO2)
Amethyst
Silicon Dioxide (SiO2) with iron impurities
Gneiss (Banded Gneiss)
Gneiss
Quartz / Vein Quartz
Quartz (Silicon Dioxide, SiO2)
Iron-Stained Quartz (Riverside Cobble)
Silicon Dioxide (SiO2) with Limonite/Hematite inclusions
Banded Gneiss
Gneiss (High-grade Regional Metamorphic Rock)
Milky Quartz
Silicon Dioxide (SiO2)
Sunstone
Oligoclase or Andesine (Plagioclase Feldspar) - (Ca, Na)((Al, Si)2Si2O8)
Not a rock
Not a rock
Not a rock
Not a rock
Milky Quartz
Silicon Dioxide (SiO2)
Banded Gneiss
Gneiss (High-grade Metamorphic Rock)
Quartz (Vein Quartz)
Silicon Dioxide (SiO2)
Quartz Pebble (Milky Quartz)
Silicon Dioxide (SiO2)
Clear Quartz
Silicon Dioxide (SiO2)
Rose Quartz
Silicon Dioxide (SiO2) with trace amounts of titanium, iron, or manganese
Obsidian
Obsidian (principally SiO2 + MgO, Fe3O4)