Limonite (Iron Ore)
Limonite (FeO(OH)·nH2O)
Category
Browse organic gemstone (not a rock or mineral in the traditional sense, but bio mineralized material) specimens identified by the Rock Identifier community.
Limonite (Iron Ore)
Limonite (FeO(OH)·nH2O)
Petrified Wood
Silicified Wood (SiO2)
Quartz
Quartz (SiO₂ - Silicon Dioxide)
Petrified Wood
Silicified wood (primarily Silicon Dioxide, SiO2)
Vesicular Basalt (Scoria)
Basalt (Extrusive Igneous Rock)
Glauconitic Sandstone (Greensand)
Glauconitic Quartz Arenite (containing Glauconite, (K,Na)(Fe3+,Al,Mg)2(Si,Al)4O10(OH)2)
Clay Brick
Ceramic structural unit (Al2O3·2SiO2·2H2O as precursor)
Red Jasper
Quartz (Silicon Dioxide) with Hematite inclusions, SiO2
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
Sandstone
Arenite (SiO2 principal)
Granite
Granite
Granite Sand (Decomposed Granite)
Grus / Quartz-Feldspar Detritus
Petrified Wood
Silicified Wood (SiO2)
Chert (with Limestone/Dolomite host)
Microcrystalline Quartz (SiO2)
Geode (Unopened)
Silica-rich concretion (SiO2)
White Jade / White Chalcedony
Nephrite Jade (Ca2(Mg,Fe)5Si8O22(OH)2) or Chalcedony (SiO2)
Yellow Jasper
Jasper, a microcrystalline variety of Quartz (SiO2) with iron inclusions
Chert / Chalcedony
Silicon Dioxide (SiO2)
Jasper (specifically Polychrome or Desert Jasper)
Silicon Dioxide (SiO2) with iron oxide and other mineral impurities
Chert (often called Flint)
Microcrystalline to cryptocrystalline quartz (SiO2)
Olivine in Basalt (Peridot)
Magnesium Iron Silicate (Mg, Fe)2SiO4 in Vesicular Basalt
Sandstone (with Iron Staining)
Clastic Sedimentary Rock (primarily Quartz, SiO2)
Almandine Garnet
Almandine (Fe3Al2(SiO4)3)
Lapis Lazuli
Sodium aluminum silicate with sulfur (main component: Lazurite [(Na,Ca)8(AlSiO4)6(SO4,S,Cl)2])
Quartz (likely) / Siliceous rock with quartz phenocrysts (if a rock fragment)
Quartz (SiO₂)
Epidote
Epidote ({Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH))
Bicolor Quartz Pebble
Silicon Dioxide (SiO2) with mineral inclusions
Sandstone (Ferruginous)
Arenite with Iron Oxides
Chert (Nodular)
Chert (SiO2 - Microcrystalline Quartz)
Pearl
Calcium Carbonate (CaCO3) with Conchiolin
Ferruginous Sandstone (Ironstone)
Clastic sedimentary rock (SiO2 with Fe2O3/FeO(OH) cement)
Chert / Flint
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Pearl
Calcium carbonate (CaCO3) as Aragonite or Calcite
Shale with Vein Infillings
Shale (a fine-grained clastic sedimentary rock). The veins could be Calcite (CaCO3), Quartz (SiO2), or other minerals.
Sandstone (Quartzose Sandstone)
Clastic sedimentary rock (primarily SiO2)
Sandstone (likely Ferruginous)
Sandstone (SiO2 with iron oxides)
Soapstone
Steatite (primarily composed of Talc, Mg₃Si₄O₁₀(OH)₂)
Chert (with Quartz vein/coating)
Microcrystalline Quartz (SiO2)
Petrified Wood
Silicified Wood (SiO2 - primarily Quartz/Chalcedony/Opal)
Sandstone (Banded)
Clastic sedimentary rock (primarily SiO2)
Limonite (Iron Ore)
Limonite (FeO(OH)·nH2O)
Petrified Wood
Silicified Wood (SiO2)