Black Sand (Magnetite Sand)
Magnetite-rich Placers (Fe3O4)
Category
Browse sedimentary rock (possibly composed of various minerals) specimens identified by the Rock Identifier community.
Black Sand (Magnetite Sand)
Magnetite-rich Placers (Fe3O4)
Biotite Gneiss
Gneiss (complex mixture including Biotite K(Mg,Fe)3AlSi3O10(F,OH)2 and Quartz/Feldspar)
Chert (Brown variety / Common Jasper)
Microcrystalline Quartz (SiO2)
Conglomerate
Conglomerate (clastic sedimentary rock)
Fluorite (Rainbow Fluorite)
Calcium Fluoride (CaF2)
Milky Quartz
Silicon Dioxide (SiO2)
Moss Agate
Silicon Dioxide (SiO2) with inclusions of Manganese or Iron oxides
Quartz Geode
Crystalline Silicon Dioxide (SiO2) within a nodule
Granite
Granite
Tree Agate
Silicon Dioxide (SiO2) - Dendritic Agate/Chalcedony
Quartzite (River Cobble)
Metamorphic Rock (composed predominantly of SiO2)
Gneiss
Gneiss (High-grade metamorphic rock)
Milky Quartz
Silicon Dioxide (SiO2)
Conglomerate
Conglomerate (clastic sedimentary rock)
Amethyst
Amethyst (Silicon Dioxide - SiO2 with iron impurities)
Sphalerite
Zinc Sulfide (Zn,Fe)S
Galena
Lead Sulfide (PbS)
Quartz Geode Fragment
Silicon Dioxide (SiO2) in a Sedimentary Host
Gneiss
Gneiss
Sandstone
Arenite
Dendritic Agate (or Dendritic Opal)
SiO2 (for Agate), SiO2·nH2O (for Opal)
Iron-stained Quartzite / Chert
Silicon Dioxide (SiO2) with Hematite/Limonite impurities
Yellow Chert (Jasper)
Microcrystalline Quartz (SiO2)
Petrified Wood
Silicified Wood (primarily SiO2)
Slate
Slate (Foliated Metamorphic Rock)
Red Sandstone
Arenite
Specular Hematite with Pyrite
Iron Oxide (Fe2O3) with Iron Sulfide (FeS2)
Granitic Sand
Detrital sediment (predominantly Quartz, Feldspar, and Mica)
Red Coral
Corallium rubrum (for precious red coral), although other species like Corallium japonicum and Paracorallium are also used.
Granite Gneiss
Felsic Gneiss
Aragonite Star Cluster
Aragonite (Calcium Carbonate, CaCO3)
Limonite Concretion (Ironstone)
Limonite / Goethite (FeO(OH)·nH2O)
Opal
Hydrated Amorphous Silica (SiO2·nH2O)
Labradorite (tumbled)
Labradorite (a plagioclase feldspar mineral between anorthite and albite; chemical formula: (Ca,Na)(Si,Al)4O8)
Chert (Nodule)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Blue Apatite
Apatite - Ca5(PO4)3(F,Cl,OH)
Geode (Unopened)
Siliceous Septarian Concretion / Geode (SiO2)
Sedimentary Breccia
Breccia (Clastic Sedimentary Rock)
Ironstone with Pyrite
Ferruginous Sandstone (Fe2O3) with minor Sulfide minerals (FeS2)
Ironstone Concretion
Siderite or Limonite Concretion
Schist
Mica Schist
Basalt (River Pebble)
Basalt (extrusive mafic rock)