Diabase (Dolerite) Cobble
Diabase / Dolerite
Category
Browse igneous and sedimentary mixture specimens identified by the Rock Identifier community.
Diabase (Dolerite) Cobble
Diabase / Dolerite
Granite
Phaneritic Felsic Igneous Rock (primarily Quartz, Feldspar, and Mica)
Basalt
Mafic Volcanic Rock (composed of Plagioclase Feldspar and Pyroxene)
Diorite
Intermediate plutonic igneous rock
Rhyolitic Tuff (Breccia Type)
Rhyolitic Pyroclastic Rock (Mixed Silicates including Quartz, Feldspar, and Volcanic Glass)
Scoria (Lava Rock)
Mafic extrusive volcanic rock (Scientific formula varies based on mineral content: primarily SiO2, MgO, and FeO)
Basaltic Scoria
Scoria (Vesicular Basalt/Andesite)
Gabbro
Gabbro (composed mainly of calcium-rich plagioclase feldspar and pyroxene)
Diorite
Phaneritic intermediate plutonic rock
Vesicular Basalt (Iron-Stained)
Mafic Volcanic Rock (Basalt)
Obsidian
Amorphous volcanic glass (70-75% SiO2)
Schorl (Black Tourmaline) in Quartz or Feldspar Matrix
NaFe3Al6(BO3)3Si6O18(OH)4 (Schorl) in Granitic Pegmatite
Gold Sheen Obsidian
Volcanic Glass (SiO2 + Fe3O4 / Gas Inclusions)
Obsidian
Obsidian (Volcanic Glass, primarily SiO2)
Obsidian
Volcanic Glass (70% or more SiO2)
Granite (with Muscovite Mica)
Phaneritic Felsic Igneous Rock (primarily Quartz SiO2, K-Feldspar KAlSi3O8, and Muscovite KAl2(AlSi3O10)(OH)2)
Basalt
Basalt (Mafic volcanic rock)
Pink Granite
Phaneritic Felsic Igneous Rock (Granite, rich in Potassium Feldspar)
Obsidian
Obsidian (Volcanic Glass, SiO2 + impurities)
Peridotite (Dunite)
Peridotite (mostly Olivine: (Mg,Fe)2SiO4)
Obsidian
Volcanic Glass (Primary composition: SiO2 - Silicon Dioxide)
Obsidian
Obsidian (Amorphous volcanic glass, SiO2 rich)
Basalt
Mafic Igneous Rock (composed primarily of Plagioclase and Pyroxene)
Black Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide) with impurities
Granodiorite
Granodiorite (calc-alkaline phaneritic igneous rock)
Amygdaloidal Basalt
Amygdaloidal Basalt with Secondary Infilling (e.g., Agate, Quartz, or Zeolite)
Obsidian
Volcanic Glass (70-75% SiO2)
Glacial Cobble (likely Granitic or Gneissic)
Granite/Gneiss Glacial Erratic
Granite Pegmatite with Tourmaline and Muscovite
Pegmatite (Feldspar: KAlSi3O8, Quartz: SiO2, Schorl: NaFe2+3Al6(Si6O18)(BO3)3(OH)3(OH))
Obsidian
Obsidian (Volcanic Glass, SiO2 + impurities)
Porphyritic Andesite
Andesite (porphyritic variety)
Labradorite (Larvikite variety)
Ternary feldspar (Anorthoclase), (Na,K)AlSi3O8
Pumice
Pumice (Vesicular Felsic Glass)
Limonite-stained Granite
Felsic Plutonic Rock with Hydrated Iron Oxides
Granite Pebble
Granite (Phaneritic Acidic Igneous Rock)
Scoria (Lava Rock)
Scoria (Extrusive Igneous Rock / Mafic Silicates)
Obsidian
Obsidian (Volcanic Glass, SiO2 + impurity isotopes)
Dalmatian Stone
Dalmatian Stone (a peralkaline igneous rock consisting of Feldspar, Quartz, and Arfvedsonite)
Obsidian
Volcanic Glass (SiO2 dominant)
Basalt with Amygdules
Amygdaloidal Basalt
Obsidian (Apache Tear)
Volcanic Glass (Amorphous Silicon Dioxide, SiO2)
Gossan (Iron Hat)
Limonitic Gossan (Fe-oxide/hydroxide complex)