Jasper
Quartz (SiO2)
sedimentary
Category
Igneous Rock (Volcanic Glass)
Browse igneous rock (volcanic glass) specimens identified by the Rock Identifier community.
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Porphyritic Basalt
Amygdaloidal Porphyritic Basalt
igneous
Porphyritic Basalt
Mafic extrusive igneous rock with porphyritic texture
igneous
Vesicular Basalt (Scoria)
Aphanitic Mafic Igneous Rock with Vesicular Texture
igneous
Dalmatian Jasper
Peralkaline Quartz-Feldspar Rock with Arfvedsonite
igneous
Milky Quartz Pebble (Iron-Stained)
Silicon Dioxide (SiO2)
mineral
Granite
Granite (Felsic Plutonic Rock)
igneous
Quartz (Druzy)
Silicon Dioxide (SiO2)
mineral
Quartz Pebble (Grit)
Silicon Dioxide (SiO2)
mineral
Pink agate (likely dyed or coated)
Microcrystalline quartz, SiO₂ (chalcedony/agate)
mineral
Basalt
Basalt (comprising Plagioclase feldspar, Pyroxene, and Olivine)
igneous
Agate
Silicon Dioxide (SiO2) - Chalcedony variant
mineral
White Agate (Chalcedony)
Silicon Dioxide (SiO2)
mineral
Porphyritic Amygdaloidal Basalt
Amygdaloidal Porphyritic Basalt (Mafic volcanic rock)
igneous
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
mineral
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
mineral
Amethyst
SiO2 (Silicon Dioxide with iron impurities)
mineral
Black Onyx
Silicon Dioxide (SiO2) - variety of Chalcedony
mineral
Scoria (Lava Rock)
Scoria (highly vesicular extrusive igneous rock)
igneous
Basalt
Basalt (Aphanitic Mafic Igneous Rock)
igneous
Porphyritic Basalt (Amygdaloidal)
Porphyritic Mafic Volcanic Rock (Amygdaloidal Basalt)
igneous
Tumbled tree agate (dendritic agate)
Cryptocrystalline quartz, SiO₂, with manganese/iron-oxide dendrites
mineral
Obsidian
Obsidian (principally SiO2 + MgO, Fe3O4)
igneous
Basalt with Scoria/Vesicular Texture
Vesicular Basalt (Iron-rich/Oxidized)
igneous
Basalt with Vesicles
Vesicular Basalt (Mafic Extrusive)
igneous
Agate Geode
Silicon Dioxide (SiO2) - Banded Chalcedony with Quartz
mineral
Diabase (also known as Dolerite)
Diabase
igneous
Olivine in Basalt (Peridot)
Magnesium Iron Silicate (Mg,Fe)2SiO4 (Mineral) / Scoriaceous Basalt (Host Rock)
igneous
Basalt
Basalt (Aphanitic Mafic Igneous Rock)
igneous
Jasper
Microcrystalline Quartz (SiO2)
sedimentary
Clear Quartz (Rock Crystal)
Silicon Dioxide (SiO2)
mineral
Basalt with Vesicular Texture
Extrusive Mafic Igneous Rock (primarily Plagioclase Feldspar and Pyroxene)
igneous
Yellow Quartz (Citrine or Iron-Stained Quartz)
Silicon Dioxide (SiO2)
mineral
Quartz
Silicon Dioxide (SiO2)
mineral
Yellow Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Obsidian
Volcanic glass (mainly SiO2 with inclusions)
igneous
Basalt Pebble
Basalt (Extrusive Mafic Igneous)
igneous
Geode with Quartz and possibly Jasper/Hematite
Quartz (SiO2) and Chalcedony (cryptocrystalline SiO2), possibly stained by iron oxides
Mineral/Sedimentary Geode
Quartz (Agate/Chalcedony variety)
Silicon Dioxide (SiO2)
mineral
Milky Quartz
Silicon Dioxide (SiO2)
mineral
Blue Sapphire
Corundum (Al2O3)
mineral
Polished ocean jasper or orbicular chalcedony
Microcrystalline quartz (SiO₂), likely chalcedony with feldspar or other mineral inclusions
mineral