Andesite
Andesite (Intermediate Extrusive Volcanic Rock)
Category
Browse igneous rock (volcanic glass) specimens identified by the Rock Identifier community.
Andesite
Andesite (Intermediate Extrusive Volcanic Rock)
Peridotite (Dunite)
Peridotite (mostly Olivine: (Mg,Fe)2SiO4)
Granodiorite
Granodiorite (Intermediate intrusive igneous rock)
Vesicular Basalt
Basalt
Basalt
Basalt (primarily composed of Plagioclase Feldspar and Pyroxene)
Basalt (River or Beach Pebble)
Basalt (Mafic Extrusive Igneous Rock)
Basalt
Basalt (Aphanitic Mafic Igneous Rock)
Basalt
Basalt (Aphanitic Mafic Volcanic Rock)
Basalt River Pebble
Basalt (Aphanitic Mafic Volcanic Rock)
Amygdaloidal Rhyolite
Amygdaloidal Rhyolite (Felsic volcanic rock)
Porphyritic Rhyolite (Red Porphyry)
Porphyritic Rhyolite (Felsic volcanic rock)
Porphyritic Rhyolite (Red Porp)
Porphyritic Rhyolite (Felsic volcanic rock)
Basalt
Basalt (Aphanitic Mafic Volcanic Rock)
Basalt (Greenstone/Trap Rock)
Basalt (dominated by plagioclase feldspar and pyroxene)
Basalt
Basalt (Mafic Extrusive Igneous Rock)
Basalt (with Plagioclase Phenocrysts)
Porphyritic Basalt
Basalt River Stone
Basalt
Jasper in Quartz (River Cobble)
Silicon Dioxide (SiO2) with Ferric Iron inclusions
Diorite
Diorite (Intermediate intrusive igneous rock)
Diorite (Polished Cobble)
Diorite (Intermediate intrusive igneous rock)
Porphyry (specifically Porphyritic Basalt or Andesite)
Porphyritic extrusive igneous rock (Mg,Fe)2SiO4 (Olivine inclusions/Plagioclase Feldspar)
Scoria
Vesicular Basalt / Scoria
Jasper or Chalcedony
Microcrystalline Quartz (SiO2)
Quartz (Iron-stained)
Silicon Dioxide (SiO2)
Basalt
Basalt (Aphanitic extrusive igneous rock)
Banded Rhyolite (likely Green Jasper/Agate variety)
Silicon Dioxide (SiO2) with mineral inclusions
Rose Quartz
Silicon Dioxide (SiO2) with trace Titanium or Manganese
Vesicular Basalt
Extrusive mafic igneous rock; primarily (Ca,Na)(Mg,Fe,Al,Si)2O6 (Pyroxene) and (Ca,Na)Al(Al,Si)Si2O8 (Plagioclase Feldspar)
Basalt with Plagioclase Phenocrysts
Porphyritic Basalt
Basalt with Quartz Vein
Basalt (SiO2 vein inclusion)
Dalmatian Jasper
Peralkaline rhyolite
Granite
Granite (Phaneritic Quartz-Feldspar Plutonic Rock)
Basalt with Pahoehoe flow texture
Vesicular Basalt (Aphanitic Mafic Igneous Rock)
Scoria (Lava Rock)
Mafic extrusive volcanic rock (Scientific formula varies based on mineral content: primarily SiO2, MgO, and FeO)
Snowflake Obsidian
Volcanic glass with Cristobalite inclusions (mostly SiO2)
Granite Cobble
Phaneritic Felsic Igneous Rock
Diorite
Phaneritic Intrusive Igneous Rock (Intermediate Composition)
Quartz Pebble
Silicon Dioxide (SiO2)
Basalt
Mafic Igneous Rock (primarily Plagioclase Feldspar and Pyroxene)
Scoria
Vesicular Basalt / Scoria (Mafic volcanic rock)
Peridot (likely, based on color and appearance)
Olivine group mineral, specifically (Mg,Fe)2SiO4 (Forsterite-Fayalite solid solution series)
Greenstone / Diabase Porphyry
Porphyritic Diabase (Micro-gabbro)