Gneiss
Gneiss
Category
Browse mineral (biogenic) specimens identified by the Rock Identifier community.
Gneiss
Gneiss
Granite
Granite (Felsic Plutonic Rock)
Granodiorite
Granodiorite
Polished orbicular jasper (likely ocean jasper or brecciated jasper)
Microcrystalline quartz (SiO₂), with iron oxides and accessory chlorite/zeolite minerals
Limonite with Quartz
Hydrated Iron Oxide Hydroxide, FeO(OH)·nH₂O with SiO₂
Greenstone / Epidosite
Epidosite (primary minerals: Epidote and Quartz)
Green Jasper
Silicon Dioxide (SiO2) with mineral inclusions
Amygdaloidal Basalt
Amygdaloidal Basalt (Mafic Extrusive volcanic rock)
Small greenish crystal/mineral fragment
Indeterminate; possibly olivine, quartz, or a green gemstone fragment
Epidote
Epidote (Ca2(Al2,Fe3+)AlSi3O12(OH))
Pegmatite (Feldspar and Quartz)
Pegmatite (KAlSi3O8 / SiO2)
Fluorite
Calcium Fluoride (CaF2)
Granite Cobble
Granite
Limonite Sandstone
Ferruginous Sandstone (Hydrated Iron Oxide)
Proustite
Proustite (Ag3AsS3)
Limonite
FeO(OH)·nH2O
Selenite (variety of Gypsum)
Calcium sulfate dihydrate (CaSO4·2H2O)
Limonite with Pyrite
Hydrated Iron Oxide Hydroxide, FeO(OH)·nH2O
Fossilized bone fragment (probable mammalian tooth or bone)
Mineralized bone, commonly hydroxyapatite [Ca5(PO4)3(OH)] replaced or impregnated by silica/calcite
Fossilized Shark Tooth
Chondrichthyes (Class)
Gneiss
Gneiss
Blue Apatite
Apatite (Ca5(PO4)3(F,Cl,OH))
Prehnite
Prehnite (Ca2Al(AlSi3O10)(OH)2)
Fluorite
Calcium fluoride (CaF2)
Malachite and Azurite on Gossan (Ironstone Matrix)
Cu2CO3(OH)2 (Malachite) on FeO(OH)·nH2O (Limonite/Gossan)
Blue Apatite
Fluorapatite (Ca5(PO4)3F)
Blue Apatite
Fluorapatite (Ca5(PO4)3F)
Granitic Pegmatite with Schorl Tourmaline
Granitic Pegmatite (Schorl: NaFe3Al6(BO3)3Si6O18(OH)4)
Blue Apatite
Calcium phosphate mineral, Ca5(PO4)3(F,Cl,OH)
Snowflake Obsidian
Obsidian with Cristobalite inclusions
Unidentified small mineral fragments
Likely quartz- or feldspar-rich material; species cannot be determined reliably from the image
Unidentified metallic-looking mineral fragment
Indeterminate; possible galena, magnetite, or metal-rich sulfide/ore fragment
Uncertain polished mineral specimen
Indeterminate; possibly quartz or feldspar with iron-oxide staining
Limonite/Goethite (Iron Ore)
Hydrous ferric oxides (FeO(OH)·nH2O)
Limonite (Iron Ore)
FeO(OH)·nH2O (Hydrated iron(III) oxide-hydroxide mixture)
Iron Ore (Limonite and Hematite)
Goethite/Limonite (FeO(OH)·nH2O) and Hematite (Fe2O3)
Azurite Malachite (Mixed)
Azurite-Malachite; Azurite: Cu3(CO3)2(OH)2 / Malachite: Cu2CO3(OH)2
Gneiss
Metamorphic Foliated Gneiss
Limonite
FeO(OH)·nH2O
Vesicular basalt (likely weathered lava rock)
Vesicular basalt; primarily plagioclase feldspar, pyroxene, and volcanic glass, with possible iron-oxide alteration
K-Feldspar (Potassium Feldspar)
Potassium Feldspar (KAlSi3O8)
Mica / Muscovite or Biotite
Phyllosilicate mineral group (e.g., KAl2(AlSi3O10)(OH)2)