Snowflake Obsidian
Spherulitic Obsidian (primarily SiO2 with Cristobalite inclusions)
igneous
Category
Synthetic (Man Made Glass)
Browse synthetic (man made glass) specimens identified by the Rock Identifier community.
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Mica Specimen (Schist / Muscovite)
Muscovite / Biotite Mica (KAl2(AlSi3O10)(F,OH)2)
metamorphic
Muscovite Mica
Muscovite (KAl2(AlSi3O10)(OH)2)
mineral
Muscovite Schist with Quartz
Muscovite (KAl2(AlSi3O10)(OH)2) in Quartz Matrix
metamorphic
Snowflake Obsidian
Volcanic Glass (SiO2 + impurities)
igneous
Muscovite Mica
Muscovite (KAl2(AlSi3O10)(OH)2)
mineral
Cobalt Blue Sea Glass
Amorphous Silica Glass (SiO2 + CoO)
mineraloid / anthropogenic material
Obsidian
Volcanic Glass (predominantly SiO2)
igneous
Snowflake Obsidian
Spherulitic Volcanic Glass (primarily SiO2)
igneous
Obsidian
Obsidian (Volcanic Glass)
igneous
Black obsidian (probable)
Volcanic glass; primarily SiO₂-rich rhyolitic composition
igneous
Muscovite
Muscovite (KAl2(AlSi3O10)(OH)2)
mineral
Muscovite Mica
KAl2(AlSi3O10)(F,OH)2
mineral
Muscovite Mica (likely on Quartz/Feldspar)
Muscovite - KAl2(AlSi3O10)(OH)2
mineral
Muscovite Mica Schist
Muscovite Schist (KAl2(AlSi3O10)(OH)2)
metamorphic
Muscovite Schist
Mica Schist (primarily KAl2(AlSi3O10)(OH)2)
metamorphic
Muscovite Schist
Mica Schist (KAl2(AlSi3O10)(OH)2)
metamorphic
Tumbled quartz crystal (likely smoky or iron-stained quartz)
Quartz, silicon dioxide (SiO₂)
mineral
Chert (variant Flint/Jasper)
Microcrystalline Opaline Silica (SiO2)
sedimentary
Rounded quartz-rich pebble
Chert or quartzite pebble (tentative; mostly microcrystalline quartz, SiO₂)
sedimentary
Weathered quartz-rich rock, possibly chert or milky quartz
Mostly microcrystalline or crystalline quartz (SiO₂), identification uncertain from photograph
mineral
Clear Quartz
Silicon Dioxide (SiO2)
mineral
Milky Quartz with inclusions
Silicon Dioxide (SiO2)
mineral
Dark flint or chert fragment
Microcrystalline quartz (SiO₂), commonly called flint when dark and nodular
sedimentary
Muscovite Mica
KAl2(AlSi3O10)(F,OH)2
mineral
Pegmatite with Mica
Granitic Pegmatite (containing Muscovite and Biotite)
igneous
Muscovite Schist with Quartz
KAl2(AlSi3O10)(OH,F)2 (Muscovite) in Schist
metamorphic
Snowflake Obsidian
Spherulitic Obsidian (Amorphous Volcanic Glass with Cristobalite inclusions)
igneous
Chert (often called Flint or River Pebble)
Chert (Microcrystalline Quartz, SiO2)
sedimentary
Green Aventurine
SiO2 (Silicon Dioxide with Fuchsite inclusions)
mineral
Muscovite Mica (with Quartz)
Muscovite (KAl2(AlSi3O10)(OH)2)
mineral
Muscovite Mica
KAl2(AlSi3O10)(F,OH)2
mineral
Obsidian
Obsidian (Volcanic glass, primarily SiO2)
igneous
Quartz with Muscovite Mica
SiO2 with KAl2(AlSi3O10)(OH)2
mineral group
Obsidian
Obsidian (Volcanic Glass)
igneous
Tumbled amethyst
Quartz, purple variety; silicon dioxide (SiO₂), colored mainly by iron impurities and irradiation
mineral
Slag
Ferrous slag (by-product of iron smelting)
Mineraloid / Anthropogenic
Chert Pebble
Microcrystalline Quartz (SiO2)
sedimentary
Muscovite Mica
Muscovite, KAl2(AlSi3O10)(OH)2
mineral
Chert (Quartz)
Silicon dioxide (SiO2)
sedimentary
Green Aventurine
Quartz containing Fuchsite (SiO2 + K(Al,Cr)2AlSi3O10(OH)2)
mineral
Muscovite
Muscovite (KAl2(AlSi3O10)(OH)2)
mineral