Obsidian
Amorphous volcanic glass (70-75% SiO2)
igneous
Category
Not A Geological Specimen
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Asphalt (Aggregate)
Bituminous macadam / Concrete Aggregate
sedimentary
Rose Quartz
Silicon Dioxide with traces of titanium, iron, or manganese (SiO2)
mineral
Green Jasper (Heliotrope / Bloodstone variety)
Silicon Dioxide (SiO₂)
sedimentary
Pyrite
Iron Disulfide (FeS2)
mineral
Quartz
Quartz (SiO₂)
Mineral
Milky Quartz
Quartz (Silicon Dioxide - SiO2)
mineral
Opalite
Synthetic Silicon Dioxide (SiO2)
mineral
Amethyst
Silicon Dioxide (SiO2) with iron impurities
mineral
Milky or Greenish Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Chert (with Quartz vein)
Chert (Silicon Dioxide, SiO2)
sedimentary
Garnet Schist
Almandine-Muscovite Schist
metamorphic
Quartz
Quartz (Silicon Dioxide - SiO2)
Mineral
Quartz
Silicon Dioxide (SiO2)
mineral
Wonderstone (Liesegang Sandstone)
Silicified Sandstone with Liesegang Rings (SiO2 + FeO(OH))
sedimentary
Quartz Geode Segment
Crystalline Silicon Dioxide (SiO2)
mineral
Granite Pebble (Salt and Pepper Granite)
Felsic Intrusive Igneous Rock (Granite)
igneous
Granite (Pink/Potassium Feldspar Granite)
Felsic Plutonic Rock (Potassium Feldspar, Quartz, Mica, and Amphibole)
igneous
Grey Quartzite Pebble
Quartzite (primarily SiO2 - Silicon Dioxide)
metamorphic
Yellow Jasper
Silicon Dioxide (SiO2) - Opaque Chalcedony
sedimentary
Amethyst Geode/Cluster
Quartz (SiO2) - variety Amethyst
Mineral
Quartz Druze (on Matrix)
Silicon Dioxide (SiO2)
mineral
Diorite (Dalmatian Stone)
Phaneritic Plutonic Diorite
igneous
Green Aventurine (Green Quartz)
Silicon Dioxide (SiO2) with inclusions of Fuchsite (K(Al,Cr)2(AlSi3O10)(OH)2)
Mineral/Metamorphic rock
Quartz
Silicon Dioxide (SiO₂)
Mineral
Jasper with Pyrite (Gold-colored inclusions)
Silicon Dioxide (SiO2) with Iron Disulfide (FeS2) inclusions
sedimentary (chemical/biological)
Pyrite
Iron Sulfide (FeS2)
mineral
Sandstone (Water-worn Pebble)
Clastic Sedimentary Rock (primarily SiO2)
sedimentary
Granodiorite with Quartz Veining
Granodiorite (containing Plagioclase Feldspar, Quartz, and Biotite/Hornblende) with Quartz (SiO2) veins
igneous
Quartz (specifically Milky Quartz/Quartzite)
Silicon Dioxide (SiO2)
Mineral
Druzy Quartz on Milky Quartz
Silicon Dioxide (SiO2)
mineral
Black Tourmaline (Schorl)
Schorl (Na(Fe^2+)3Al6(Si6O18)(BO3)3)(OH)3(OH))
mineral
Fluorite
Calcium Fluoride (CaF2)
mineral
Build-A-Bear Plush (Non-Geological)
Polyester fibers (C10H8O4)n and Synthetic Polymers
Anthropogenic / Non-mineral
Coarse-grained Granite (Quartz and Feldspar dominated)
Granitoid (KAlSi3O8 – NaAlSi3O3 – CaAl2Si2O8 – SiO2)
Igneous
Basalt Pebble
Basalt (Extrusive Mafic Igneous)
igneous
Quartzite (Beach Pebble)
Quartzite (primarily SiO2)
metamorphic
Yellow Jasper
Silicon Dioxide with Iron inclusions (SiO2)
sedimentary
Limonite Sandstone
Ferruginous Sandstone (Hydrated Iron Oxide)
sedimentary
Pebble (likely Sandstone or Granitic Pebble)
Clastic Sediment (or specific rock type, e.g., Arenite, Granitoid Pebble)
Rock (likely Sedimentary)
Yellow Jasper
Jasper (Silicon Dioxide, SiO2)
sedimentary
Rose Quartz
Silicon Dioxide (SiO2)
mineral