Likely polished black stone or obsidian
Obsidian (volcanic glass), chiefly SiO₂
Category
Browse man made material specimens identified by the Rock Identifier community.
Likely polished black stone or obsidian
Obsidian (volcanic glass), chiefly SiO₂
Jasper (Mookaite style)
Silicon Dioxide (SiO2) with iron and manganese inclusions
Petrified Wood
Silicified Wood (primarily SiO2)
Sandstone (Quartzose Sandstone)
Clastic Sedimentary Rock (primarily SiO2)
Orbicular jasper / brecciated jasper
Silica-rich microcrystalline quartz (chalcedony), commonly with iron oxides and altered volcanic fragments
Chert / Flint (with quartz or calcite inclusion)
Silicon dioxide (SiO2)
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
Carnelian Beads
Silicon Dioxide (Variety of Chalcedony), $SiO_2$
Jasper
Silicon Dioxide (SiO2)
Milky quartz
Quartz (silicon dioxide, SiO₂)
Tumbled blue-gray chalcedony (likely blue agate)
Chalcedony, microcrystalline quartz (SiO₂)
Granite
Intrusive Felsic Igneous Rock (composed mainly of Quartz, Plagioclase, Alkali Feldspar, Biotite, and Amphibole)
Quartzite
Quartzite (primarily SiO2)
Moss agate bracelet
Chalcedony (microcrystalline quartz, SiO₂) with chlorite/amphibole inclusions
Amethyst cluster
Quartz, SiO₂; purple coloration is caused mainly by iron-related defects and natural irradiation
Petrified Wood (Black / Carbonized)
Silicon Dioxide (Quartz/Chalcedony replacing Organic Matter)
Petrified Wood
Silicified Wood (primarily SiO2)
Petrified Wood
Silicified Wood (SiO2)
Chert (Flint)
Silicon Dioxide (SiO2)
Polished dendritic jasper or agate slab
Microcrystalline quartz (SiO₂), likely jasper with chalcedony and iron/manganese dendrites
Rhodonite
Rhodonite (MnSiO3)
Sandstone Cobble
Arenite (Sandstone)
Chert or chalcedony fragment (possibly agate)
Microcrystalline quartz, SiO₂
Colorless faceted gemstone, likely cubic zirconia
Cubic zirconia (zirconium dioxide, ZrO₂); visual confirmation is unavailable
Gneiss pebble
Banded gneiss, commonly quartz–feldspar–biotite gneiss
Petrified Wood
Silicified Wood (primarily Quartz / Chalcedony: SiO2)
Colorless faceted gemstone (likely cubic zirconia)
Cubic zirconia, ZrO₂ (synthetic zirconium dioxide); possibly synthetic glass or lab-grown diamond
Diamond
Carbon (C)
Diamond (Green tinted)
Carbon (C) with trace impurities or lattice defects
Quartzite (River Pebble)
Metamorphosed Quartz-rich Sandstone (SiO2)
Siltstone/Sandstone (possibly Wonderstone or Picture Sandstone)
Clastic Sedimentary Rock (primarily SiO2 with Iron Oxide inclusions)
Quartz with Mica/Chlorite inclusions
Silicon Dioxide (SiO2) with phyllosilicate inclusions
Polished black obsidian pyramid/block
Obsidian — natural volcanic glass, chiefly rhyolitic silica (approximately 70–75% SiO₂)
Likely serpentinized ultramafic rock (serpentinite)
Serpentinite; chiefly serpentine-group minerals, Mg₃Si₂O₅(OH)₄, possibly with magnetite, chromite, and brucite
Milky Quartz Pebble
Quartz (Silicon Dioxide, SiO2)
Limestone
Calcium Carbonate (CaCO3)
Calcite specimen
Calcite (calcium carbonate, CaCO₃), likely crystalline limestone or cave-calcite aggregate
Serpentinite
Serpentinite (Mg, Fe, Ni)₃Si₂O―(OH)₄
Quartzite
Quartzite (primarily SiO2)
Rose Quartz
Silicon dioxide (SiO2) with traces of titanium, iron, or manganese
Slag (Industrial Glassy Byproduct)
Ferro-silicate Slag
Limestone
Calcium Carbonate (CaCO3)