Amethyst (Quartz)
Amethyst (Silicon Dioxide with Iron impurities, SiO2)
mineral
Category
Industrial Byproduct (Often Confused With Igneous Rocks Or Meteorites)
Browse industrial byproduct (often confused with igneous rocks or meteorites) specimens identified by the Rock Identifier community.
Basalt (with possible iron oxide staining)
Mafic Igneous Rock (primarily Plagioclase and Pyroxene)
igneous
Basalt with Quartz Veins
Vesicular or aphanitic Basalt with SiO2 (Quartz) intrusions
Igneous
Gneiss
Gneiss (Metamorphic rock composed primarily of quartz, feldspar, and mica)
metamorphic
Blue Quartzite (River Pebble)
Quartzite (primarily SiO2 with Dumortierite or Crocidolite inclusions)
metamorphic
Larvikite
Monzonite (intermediate intrusive igneous rock containing plagioclase, alkali feldspar, augite, and biotite)
igneous
Bronzite
Enstatite (var. Bronzite), (Mg,Fe)SiO3
mineral
Sodalite
Sodalite (Na8Al6Si6O24Cl2)
mineral
Red Sandstone
Clastic Terrigenous Sedimentary Rock (composed mostly of SiO2 with Fe2O3)
sedimentary
Porphyritic Rhyolite (Birdseye Rhyolite)
Rhyolite (Porphyritic texture)
igneous
Anthracite Coal
Anthracite (Carbon-rich metamorphic coal)
metamorphic
Banded Agate (Brazilian Agate Slice)
Chalcedony (Silicon Dioxide / SiO2)
Mineral
Quartz with Hematite Inclusions
Silicon Dioxide (SiO2) with Ferric Oxide (Fe2O3)
mineral
Obsidian
Obsidian (Volcanic Glass) SiO2 (70% or more)
igneous
Red Jasper
Jasper (Silicon Dioxide with Iron Oxide impurities), SiO2
sedimentary
Bauxite
Bauxite (principal ore of aluminum, primarily Al(OH)3)
sedimentary
Sandstone Beach Pebble
Clastic Sedimentary Rock (primarily Quartz with Iron Oxide coating)
sedimentary
Ironstone (likely Ferruginous Siltstone/Sandstone)
Ferruginous sedimentary rock (FeOx-rich clastic)
sedimentary
Aura Quartz (Pink/Rose Aura Quartz)
Silicon Dioxide (SiO2) bonded with Platinum and/or Silver
mineral
Amethyst
Amethyst (Silicon Dioxide - SiO2 with iron impurities)
mineral
Moonstone with Black Tourmaline
Orthoclase (KAlSi3O8) with Schorl inclusions
mineral
Quartz with Mica inclusions (Pegmatite)
Silicon Dioxide (SiO2) with Muscovite/Biotite inclusions
igneous
Red Jasper (possibly Wonderstone)
Silicon Dioxide (SiO2) with iron oxide inclusions
sedimentary
Amethyst
Silicon Dioxide (SiO2) with iron impurities
mineral
Basalt
Basalt
igneous
Ferruginous Sandstone (River Pebble)
Clastic Sedimentary Rock (primarily SiO2 with Fe2O3 cement)
sedimentary
Granite
Phaneritic intrusive igneous rock (Quartz, Feldspar, Mica)
igneous
Biotite (Mica)
Biotite - K(Mg,Fe)3AlSi3O10(F,OH)2
mineral
Muscovite (Mica)
Muscovite - KAl2(AlSi3O10)(OH)2
Mineral
Marble
Recrystallized Calcite (CaCO3)
metamorphic
Jasper and Quartz River Pebble
Silicon Dioxide (SiO2) with impurities
sedimentary
Rhyolite
Rhyolite
igneous
Diamond
Carbon (C)
mineral
Jasper
Silicon dioxide (SiO2) with iron oxide and clay inclusions
sedimentary
Granite or Pegmatite with Mica
Granitoid
igneous
Amethyst
Quartz (Silicon Dioxide) with Ferric Iron impurities - SiO2
mineral
Red Sandstone
Arenite (primarily Quartz with Hematite cement)
sedimentary
Granite
Granite (Felsic Intrusive Igneous Rock)
igneous
Quartzite Pebble
Quartzite (primarily SiO2)
metamorphic
Basalt (Vesicular or Scoriaceous)
Aphanitic Mafic Volcanic Rock
igneous
Limestone (specifically Iron-stained or Argillaceous Limestone)
Calcium Carbonate (CaCO3) with Iron Oxide (Fe2O3) impurities
sedimentary
Amethyst
Silicon Dioxide (SiO2) with iron impurities
mineral