Opal
Hydrated amorphous form of silica (SiO2·nH2O)
Category
Browse sedimentary or igneous fragment specimens identified by the Rock Identifier community.
Opal
Hydrated amorphous form of silica (SiO2·nH2O)
Jasper (Red and Yellow)
Silicon Dioxide (SiO2) with iron oxide impurities
Opal
Hydrated Silica (SiO2·nH2O)
Limestone
Calcium Carbonate (CaCO3)
Terrazzo (with Marble and Granite fragments)
Cementitious or resinous composite containing Calcium Carbonate (CaCO3) and Silicates
Dalmation Jasper (or Dalmation Stone)
Dalmation Stone (composed of Perthite, Quartz, and Arfvedsonite)
Dalmatian Stone (often called Dalmatian Jasper)
Peralkaline Feldsphathic Igneous Rock
Ferruginous Sandstone (with Iron Oxide staining)
Clastic Sedimentary Rock - Quartz Arenite/Wacke
Red Sandstone
Arenite (ferruginous sandstone)
Pyrite (Fool's Gold)
Iron Disulfide (FeS2)
Black Jasper
Silicon Dioxide (SiO2) with inclusions
Red Jasper (possibly Red Coral or dyed Howlite)
Silicon Dioxide (SiO2) with Iron Oxide inclusions
Sandstone or Mudstone with Iron Staining
Ferruginous Sandstone/Mudstone
River Stone (Basalt or Siltstone with banding)
Polished Basaltic or Siliciclastic River Cobble
Chert (or Flint)
Chert (microcrystalline or cryptocrystalline quartz, SiO2)
Sandstone with Secondary Mineral Encrustation
Arenite with Silica/Calcite deposits (SiO2 or CaCO3)
Yellow Calcite
Calcium Carbonate (CaCO3)
Pyrite
Iron Sulfide (FeS2)
Pyrite and Sunstone
Iron Sulfide (FeS2) and Plagioclase Feldspar ((Ca,Na)Al(Al,Si)Si2O8)
Carnelian
Carnelian (SiO2)
Quartz Pebble
Silicon Dioxide (SiO2)
Clear Quartz
Quartz (Silicon Dioxide, SiO2)
Aventurine Quartz
Silicon Dioxide (SiO2) with inclusions (typically Fuchsite/Mica)
Ruby (Pinkish-Red)
Corundum (Al2O3 with Chromium trace)
Quartz
Silicon Dioxide (SiO2)
Magnetite
Magnetite (Fe3O4)
Milky Quartz
Silicon Dioxide (SiO2)
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
Dalmatian Jasper / Dalmatian Stone
Peralkaline Rock (Silicon Dioxide with Amphibole inclusions)
Dalmatian Stone
Peralkaline rhyolite with arfvedsonite (formerly incorrectly called Dalmatian Jasper)
Ruby (Raw Corundum)
Corundum (Aluminum Oxide with Chromium), Al2O3:Cr
Yellow Aventurine (specifically a carved crescent moon)
Silicon Dioxide (SiO2) with inclusions
White Quartz Pebble
Silicon Dioxide (SiO2)
Schist
Crystalline Metamorphic Rock (Schistose)
Blue Sapphire
Corundum (Al2O3 with trace Titanium and Iron)
Milky Quartz
Silicon Dioxide (SiO2)
Obsidian
Volcanic Glass (Primary composition: SiO2 - Silicon Dioxide)
Dalmatian Jasper
Peralkaline Quartz-Feldspar Rock with Arfvedsonite
K2 Jasper (K2 Granite)
Azurite in Granite (Biotite Granite containing Azurite)
Dalmatian Stone (commonly Dyed)
Dalmatian Jasper (Peralkaline igneous rock)
Dalmatian Stone
Dalmatian Jasper (actually a Peralkaline Igneous Rock)
Dark Igneous Rock (Likely Basalt or Diabase)
Basalt (extrusive igneous rock) or Diabase (intrusive igneous rock - also known as Dolerite), largely composed of plagioclase feldspar, pyroxene (augite), and sometimes olivine and amphibole. Exact mineralogy would require thin section analysis.