Goethite / Limonite Concretion
Iron Hydroxide Oxide (FeO(OH))
Category
Browse mineraloid like synthetic material specimens identified by the Rock Identifier community.
Goethite / Limonite Concretion
Iron Hydroxide Oxide (FeO(OH))
Quartz pebble
Silicon dioxide (SiO2)
Greenstone / altered basalt fragment
Likely chlorite–epidote–actinolite altered basalt; exact identification requires testing
Chert
Microcrystalline Quartz (SiO2)
Chert (often called Flint or River Pebble)
Chert (Microcrystalline Quartz, SiO2)
Chert (Jasper)
Silicon Dioxide (SiO2)
Gray Granite
Granite (Phaneritic igneous rock)
Chert (Flint Nodule)
Microcrystalline or cryptocrystalline quartz (SiO2)
Granite (Dioritic variant)
Granite (Phaneritic Igneous Rock)
Chert (with Quartz Druzy)
Microcrystalline Silica (SiO2)
Limestone
Calcium Carbonate (CaCO3)
Silver (Morgan Dollar)
Native Silver (Ag) - 90% Silver, 10% Copper alloy
Obsidian
Obsidian (principally SiO2)
Limestone
Calcium Carbonate (CaCO3)
Chert (Flint Nodules)
Microcrystalline Quartz (SiO2)
Limonite (Iron Ore)
Limonite (FeO(OH)·nH2O)
Fossilized Coral (Favosites)
Favosites (Extinct Tabulate Coral)
Slate
Slate (Foliated metamorphic rock)
Jasper
Silicon dioxide (SiO2)
Chert / Jasper
Microcrystalline Quartz (SiO2)
Granodiorite
Granodiorite
Sandstone
Arenite (SiO2 based)
Petrified Wood
Silicified Wood (SiO2)
Diamond (Faceted)
Carbon (C)
Sedimentary Rock (Limestone or Siltstone pebble)
Sedimentary rock fragment
Sandstone (with Manganese staining)
Arenite (composed primarily of SiO2)
Coquina or Coral Fossil
Biogenic Limestone (Calcite/Aragonite)
Sandstone
Arenite (primarily SiO2)
Olivine (Peridot)
Magnesium Iron Silicate (Mg, Fe)2SiO4
Sandstone
Arenite (SiO2 principal)
Chert (or Chalcedony)
Microcrystalline Quartz (SiO2)
Chert / Flint
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Chert (Chalky Flint Node)
Chert (Microcrystalline Quartz, SiO2)
Sandstone (Ferruginous / River-worn Cobble)
Sandstone (SiO2 with iron oxide impurities)
Sandstone
Arenite (composed mainly of SiO2)
Sandstone (likely Siltstone or fine-grained Sandstone)
Sedimentary Rock (Clastic)
Petrified Wood
Silicified Wood (primarily SiO2)
Chert
Microcrystalline silica (SiO2)
Yellow Jasper
Silicon Dioxide (SiO2) with iron inclusions
Biotite on Matrix
Biotite (K(Mg,Fe)3AlSi3O10(F,OH)2)
Sandstone
Arenite (SiO2 based)
Sandstone
Arenite (primarily SiO2)