Mahogany Obsidian
Volcanic Glass with Hematite/Magnetite inclusions
Category
Browse mineral like byproduct (often mistaken for igneous rock or meteorite) specimens identified by the Rock Identifier community.
Mahogany Obsidian
Volcanic Glass with Hematite/Magnetite inclusions
Amygdaloidal Rhyolite
Amygdaloidal Rhyolite (Felsic volcanic rock)
Agate (or Banded Agate)
Agate (a variety of Chalcedony, which is a cryptocrystalline form of Quartz); Chemical Formula: SiO₂ (Silicon Dioxide)
Red Scoria (Lava Rock)
Scoria (Vesicular Basalt/Andesite)
Snowflake Obsidian
Volcanic glass (SiO2) with Cristobalite (SiO2) inclusions
Chert (Nodule)
Silicon Dioxide (SiO2)
Hypersthene
Hypersthene (Magnesium Iron Silicate - (Mg,Fe)SiO3)
Garnet (likely Almandine)
Almandine (Fe3Al2(SiO4)3)
Milky Quartz
Silicon Dioxide (SiO2)
Milky Quartz
Silicon Dioxide (SiO2)
Granite
Granite
Smoky Quartz
Smoky Quartz (Silicon Dioxide, SiO2)
Banded Agate (Jasper-Agate)
Silicon Dioxide (SiO₂)
Red Sandstone
Arenite (Ferruginous Sandstone)
Shale
Shale (clastic sedimentary rock)
Greenstone (Greenschist facies)
Greenschist (composed primarily of Chlorite, Actinolite, and Epidote)
Prehnite
Prehnite - Ca2Al(AlSi3O10)(OH)2
Agate
Banded Chalcedony (SiO2 - Silicon Dioxide)
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
Jasper Agate
Silicon dioxide (SiO2)
Sandstone
Arenite (primarily SiO2)
Gneiss
Gneiss (High-grade regional metamorphic rock)
Cobaltian Calcite (Cobaltoan Calcite)
Cobaltian Calcite (CaCO3 with Co2+ substitution)
Basalt
Mafic volcanic rock (Primary minerals: Plagioclase feldspar, Pyroxene)
Carnelian Agate
Silicon Dioxide (SiO2) with high Iron Oxide impurities
River Siltstone / Mudstone Pebble
Siltstone (composed of mixed silicate and carbonate minerals)
Fluorite (specifically Rainbow Fluorite or Purple Fluorite)
Calcium Fluoride (CaF2)
Blue Dyed Agate Geode
Chalcedony (cryptocrystalline Quartz), SiO2
Amethyst
Quartz variety; SiO2 (Silicon Dioxide)
Carnelian Agate
Silicon dioxide (SiO2) - Chalcedony variety
Greenstone Porphyry
Porphyritic Metavolcanic Rock
Fossilized Gastropod (Snail)
Class Gastropoda (internal mold or 'steinkern')
Amygdaloidal Basalt with Quartz/Zeolite Infill
Amygdaloidal Basalt (extrusive volcanic rock with SiO2 or CaAl2Si3O10·3H2O infill)
Granite Pebble
Granite (Phaneritic intrusive igneous rock comprising Quartz, Feldspar, and Mica)
Gneiss
Gneiss
Chert (Jasper/Flint Pebble)
Microcrystalline quartz (SiO2)
Sandstone (Quartzite-rich Pebble)
Arenite (composed primarily of SiO2)
Milky or Iron-Stained Quartz
Quartz (Silicon Dioxide, SiO2)
Orange Calcite
Calcite (Calcium Carbonate, CaCO3)
Ferruginous Sandstone
Clastic sedimentary rock (primarily Quartz with Iron Oxide cement)
Serpentine
Serpentine group, including Antigorite, Lizardite, and Chrysotile (Mg,Fe,Ni,Al,Zn,Mn)2-3(Si,Al,Fe)2O5(OH)4
Greenstone
Greenschist