Prehnite
Ca2Al(AlSi3O10)(OH)2
Category
Browse mineral like (anthropogenic) specimens identified by the Rock Identifier community.
Prehnite
Ca2Al(AlSi3O10)(OH)2
Sandstone
Sandstone (clastic sedimentary rock)
Quartz with Sericite and Cinnabar
Silicon Dioxide (SiO2) with muscovite/sericite and mercury sulfide (HgS)
Conglomerate
Conglomerate (Sedimentary Rock)
Muscovite Mica
Muscovite (KAl2(AlSi3O10)(OH)2)
Sandstone with Manganese Dendrites
Clastic Sedimentary Rock (SiO2 based with MnO2 inclusions)
Black Obsidian
Amorphous volcanic glass (SiO2 + impurities)
Banded Sandstone (Beach Pebble)
Quartz Arenite Sandstone
Blue Apatite
Apatite, Ca5(PO4)3(F,Cl,OH)
Native Copper
Native Copper (Cu)
Snowflake Obsidian
Vitreous Volcanic Glass (Siliceous Obsidian with Cristobalite inclusions)
Granitic Pegmatite
Granite Pegmatite (principally KAlSi3O8, SiO2, and KAl2(AlSi3O10)(OH)2)
Sandstone
Clastic sedimentary rock (primarily SiO2)
Sandstone with Mineral Veining or Crust
Sedimentary Sandstone (mostly SiO2 with Fe2O3 tinting)
Quartz Geode Fragment
Silicon Dioxide (SiO2)
Limonite/Ironstone
Limonite (FeO(OH)·nH2O)
Potassium Feldspar (Orthoclase)
KAlSi3O8 (Potassium Aluminum Silicate)
Gneiss
Gneiss
Schist
Mica Schist
Pegmatite (with Quartz and Feldspar)
Granitic Pegmatite
Erythrite
Erythrite (Cobalt Bloom) - Co3(AsO4)2·8H2O
Garnet
Garnet Group (Silicate Minerals), formula varies e.g., Alm: Fe3Al2(SiO4)3
Petrified Wood
Silicified Wood / Fossilized Wood (SiO2)
Fluorite
Calcium Fluoride (CaF2)
Sandstone (likely Arkose or Lithic)
Clastic sedimentary rock (SiO2 + impurities)
Chrysocolla on Matrix
Hydrated copper phyllosilicate (Cu,Al)2H2Si2O5(OH)4·nH2O
Limonite (Iron Ore)
Hydrated ferric oxide mixture (FeO(OH)·nH2O)
Blue Apatite
Fluorapatite (Ca5(PO4)3F)
Dendrite (Manganese Oxide Dendrites)
Psilomelane or Pyrolusite on Matrix (typically MnO2)
Concretion
Septarian Concretion
Quartz Vein / Quartz Matrix
Silicon Dioxide (SiO2)
Gossan
Ferruginous gossan (Iron-rich capping)
Fluorite
Calcium fluoride (CaF2)
Greenstone
Metabasalt (Greenstone)
Limonite Concretion
Limonite (Hydrated iron(III) oxide-hydroxides, FeO(OH)·nH2O)
Sandstone
Arenite (typically SiO2 based)
Quartz on Schist
Silicon Dioxide (SiO2) on Foliated Metamorphic Rock
Mahogany Obsidian
Volcanic Glass with Hematite/Magnetite (SiO2 + Fe2O3)
Graphic Granite / Pegmatite
Graphic Granite (Alkali Feldspar and Quartz)
Pyrite in Matrix with Copper Alterations
Iron Sulfide (FeS2) with secondary Copper carbonates/sulfides
Mahogany Obsidian
Volcanic glass (SiO2 with Hematite or Magnetite inclusions)
Limonite (Limonitic Sandstone)
Hydrated Iron(III) Oxide-Hydroxide ($FeO(OH)·nH_2O$)