Granite Cobble
Granite
Category
Browse igneous specimens identified by the Rock Identifier community.
Granite Cobble
Granite
Mahogany Obsidian
Volcanic glass (SiO2 with Hematite or Magnetite inclusions)
Basalt
Basalt
Granite
Granite (composed primarily of Quartz SiO2 and Feldspar (KAlSi3O8 – NaAlSi3O8 – CaAl2Si2O8))
Diorite (Salt and Pepper Rock)
Phaneritic Plutonic Diorite (Plagioclase Feldspar + Amphibole/Biotite)
Basalt
Basalt (Mafic volcanic rock)
Snowflake Obsidian
Spherulitic Obsidian (primarily SiO2 with Cristobalite inclusions)
Black Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
Basalt
Mafic volcanic rock (Primary minerals: Plagioclase feldspar, Pyroxene)
Basalt with Quartz/Feldspar Vein
Amygdaloidal Basalt with Plutonic intrusion (SiO2/KAlSi3O8)
Diorite
Phaneritic Intermediate Plutonic Rock (Diorite)
Pink Granite (Gneissic transition)
Pink Biotite Granite
Granite
Granitoid (composition typically SiO2, Al2O3, K2O, Na2O)
Granite
Granite (Phaneritic intrusion / SiO2 + KAlSi3O8 + NaAlSi3O8)
K2 Jasper (K2 Granite)
Azurite-in-Granite
Thunderegg (Agetized Geode nodule)
Rhyolitic Agate Nodule (SiO2 filling volcanic cavities)
Basalt
Basalt (Mainly Plagioclase Feldspar and Pyroxene)
Porphyritic Basalt (Chinese Writing Stone/Flower Stone)
Porphyritic Basalt (primarily Plagioclase Feldspar in a Mafic groundmass)
Basalt
Basalt (Aphanitic-to-porphyritic mafic volcanic rock)
Vesicular Basalt with Quartz/Chalcedony
Vesicular Basalt (primarily Plagioclase, Pyroxene, and Olivine with SiO2 infill)
Porphyritic Andesite (often called Chinese Writing Stone)
Porphyritic Basaltic Andesite with Feldspar Phenocrysts
Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with impurities)
Obsidian
Obsidian (principally SiO2 + MgO, Fe3O4)
Obsidian
Obsidian (Volcanic Glass), primarily SiO2
Basalt
Mafic extrusive volcanic rock (composed primarily of Plagioclase feldspar and Pyroxene)
Black Obsidian
Volcanic Glass (predominantly SiO2)
Granite
Phaneritic plutonic rock (primarily Quartz, Feldspar, and Mica)
Basalt Pebble
Vesicular Basalt
Pumice
Pumice (a highly vesicular volcanic glass)
Andesite
Andesite (Intermediate Extrusive Volcanic Rock)
Pumice
Pumice (Vitreous volcanic rock)
Porphyry
Porphyritic Rhyolite or Andesite
Mahogany Obsidian
Obsidian (SiO2 + Fe2O3)
Granite
Granitoid
Quartz Vein Rock
Quartz (Silicon Dioxide, SiO2)
Basalt with Amygdules
Amygdaloidal Basalt
Polished Basalt
Basalt (Mafic volcanic rock)
Amygdaloidal Basalt with Agate/Chalcedony Infills
Amygdaloidal Basalt (Composition: SiO2 and (Mg,Fe)2SiO4 in matrix; SiO2 in amygdule)
Obsidian
Volcanic Glass (SiO2)
Amygdaloidal Basalt
Amygdaloidal Basalt (Mafic volcanic rock including secondary mineral infills)
Vesicular Basalt (or Scoraceous Basalt)
Basalt with vesicular texture
Granite
Granite (Felsic Plutonic Rock)