Amethyst
Silicon Dioxide (SiO2)
Category
Browse mineral (man made glass, not natural) specimens identified by the Rock Identifier community.
Amethyst
Silicon Dioxide (SiO2)
Onyx (Black Onyx)
Onyx (Silicon Dioxide, SiO2)
Tumbled jasper, likely red/brown jasper
Microcrystalline quartz (chalcedony), SiO₂, colored chiefly by iron oxides
Synthetic Sapphire and Ion-X Glass
Single-crystal Alumina (Al2O3) and Ion-strengthened Aluminosilicate Glass
Amethyst
Silicon Dioxide (SiO2)
Herkimer Diamond (Quartz Crystal)
Silicon Dioxide (SiO2)
Hag Stone
Perforated Sedimentary Rock (typically Flint, Chert, or Limestone)
Amethyst
Amethyst (Silicon Dioxide - SiO2 with iron impurities)
Mixed pebble collection, including likely flint, quartzite, and fossil material
Varied silicate rocks; visible specimen may include chert (microcrystalline SiO₂), quartzite, and a possible fossil
Smoky Quartz
Quartz (Silicon Dioxide, SiO2)
Fulgurite
Lechatelierite (vitreous silica / silica glass)
Pumice
Pumice (volcanic glass)
Blue Topaz
Al2SiO4(F,OH)2 (Aluminum silicate fluoride hydroxide)
Clear Quartz
Silicon Dioxide (SiO2)
Amethyst
Silicon Dioxide (SiO2) with iron impurities
Tumbled milky quartz
Quartz, silicon dioxide (SiO₂)
Tumbled epidote-bearing rock (likely epidote–quartz–feldspar aggregate)
Epidote-rich metamorphic rock; minerals likely epidote (Ca₂(Al,Fe)₃Si₃O₁₂(OH), quartz, feldspar, and dark amphibole/biotite)
Muscovite Mica
Muscovite (Potassium Aluminum Silicate Hydroxide Fluoride), KAl2(AlSi3O10)(OH,F)2
Chert
Microcrystalline quartz (SiO2)
Banded Chert
Microcrystalline Quartz (SiO2)
Obsidian
Volcanic Glass (Amorphous silicon dioxide with trace impurities)
Sandstone (likely Greywacke or Siltstone variety)
Arenite / Siltstone (primarily SiO2)
Chert Nodule
Microcrystalline Quartz (SiO2)
Smoky Quartz
Silicon Dioxide (SiO2) with aluminum impurities
Quartz (Citrine/Milky variety)
Silicon Dioxide (SiO2)
Quartz Pebble (River Agate / Chalcedony)
Silicon Dioxide (SiO2)
Blue Topaz
Al2SiO4(F,OH)2 (Fluorine-bearing aluminum silicate)
River Stone (likely Mudstone or Siltstone)
Lutite (Clastic sedimentary rock composed of clay and silt-sized particles)
Rough Diamond
Diamond (pure Carbon, C)
Diamond
Pure Carbon (C)
Green Quartz (Prasiolite variant or Aventurine)
Silicon Dioxide (SiO2)
Milky Quartz Pebble (Beach Agate / Quartz)
Silicon Dioxide (SiO2)
Clear Quartz (Rock Crystal)
Silicon Dioxide (SiO2)
Sandstone
Arenite (composed primarily of SiO2)
Granite (weathered pebble)
Granite (plutonic igneous rock)
Clear Quartz
Silicon Dioxide (SiO2)
Citrine Quartz
Crystalline Quartz (SiO2) with iron impurities
Sunstone
Plagioclase Feldspar (Na,Ca)(Al,Si)4O8
Smoky Quartz
Silicon Dioxide (SiO2) with natural radiation induced color centers
Quartz (Milky/Smoky variety)
Silicon Dioxide (SiO2)
Granite / Diorite (Granodiorite)
Granodiorite / Quartz Diorite
Smoky Quartz
Silicon Dioxide (SiO2)