Basalt
Basalt (composition predominately plagioclase feldspar and pyroxene)
igneous
Category
Sedimentary (Volcanic)
Browse sedimentary (volcanic) specimens identified by the Rock Identifier community.
Carnelian
Carnelian (SiO2)
mineral
Turquoise in Matrix
Hydrated phosphate of copper and aluminium: CuAl6(PO4)4(OH)8·4H2O
mineral
Amethyst
SiO2 (Silicon Dioxide with Iron impurities)
mineral
Larimar
Pectolite (NaCa2Si3O8(OH))
mineral
Howlite and Purple Amethyst Druzy
Calcium Borosilicate Hydroxide (Howlite) and Silicon Dioxide (Quartz/Amethyst)
mineral
Turquoise
Turquoise (Hydrated phosphate of copper and aluminium) CuAl6(PO4)4(OH)8·4H2O
mineral
Granodiorite
Granodiorite
igneous
Olivine (Peridot)
Magnesium Iron Silicate (Mg, Fe)2SiO4
mineral
Olivine (Peridot)
Magnesium Iron Silicate (Mg,Fe)2SiO4
mineral
Scoria (Lava Rock)
Scoria
igneous
Sandstone (Weathered Cobble)
Clastic Sedimentary Rock (primarily SiO2)
sedimentary
Snowflake Obsidian
Spherulitic Volcanic Glass (primarily SiO2 with Cristobalite inclusions)
igneous
Ferrous Slag
Fused calcium-iron silicates (Industrial Slag)
Anthropogenic/Industrial byproduct
Tektite (Indochinite)
Tektite (Natural Glass, SiO2 + Al2O3)
mineral
Basalt
Mafic volcanic rock (primarily plagioclase feldspar and pyroxene)
Igneous
Tektite (Indochinite)
Tektite (Lechatelierite-rich silica glass)
Mineral-like (Natural Glass)
Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
igneous
Basalt
Basalt (composition of Plagioclase feldspar, Pyroxene, and Olivine)
igneous
Satin Spar (Selenite variant)
Gypsum (Calcium Sulfate Dihydrate, CaSO4·2H2O)
mineral
Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
Igneous
Conglomerate (Puddingstone)
Conglomerate (specifically, clastic sedimentary rock)
Sedimentary
Conglomerate
Conglomerate (a clastic sedimentary rock)
Sedimentary
Obsidian (worked into an arrowhead profile)
Obsidian (volcanic glass), primarily SiO2 (Silicon Dioxide)
igneous
Obsidian (Apache Tear)
Obsidian / Amorphous Volcanic Glass (main component: SiO2)
igneous
Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
Igneous
Obsidian
Volcanic Glass (Primary composition: SiO2 - Silicon Dioxide)
igneous
Obsidian Arrowhead
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
igneous
Moss Agate
Chalcedony (Silicon Dioxide / SiO2)
mineral
Larimar
Pectolite (Blue variety), NaCa2Si3O10(OH)
mineral
Sandstone (with Iron Staining)
Clastic sedimentary rock (primarily Quartz with Limonite/Goethite staining)
sedimentary
River Rocks (Basalt and Sedimentary Stones)
Mafic Igneous Rock (Basalt) and Clastic Sedimentary Rock
igneous and sedimentary
Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with impurities)
igneous
Quartz Vein in Host Rock
Silicon Dioxide (SiO2) in Rhyolitic Matrix
igneous
Basalt
Basalt (Mafic volcanic rock, primarily Plagioclase and Pyroxene)
igneous
Black Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
igneous
Sandstone
Clastic sedimentary rock (primarily SiO2)
sedimentary
Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with impurities)
igneous
Carnelian Agate
Red Chalcedony (SiO2 with Iron Oxide impurities)
mineral
Diorite
Diorite (intermediate intrusive igneous rock)
igneous
Agate (Polished Nodule)
Agate (Silicon Dioxide, SiO2)
mineral
Red Jasper
Silicon dioxide (SiO2)
mineral