Biotite mica
Biotite, a potassium-rich mica in the annite–phlogopite series; approximate formula K(Mg,Fe)₃AlSi₃O₁₀(F,OH)₂
mineral
Category
Not A Geological Specimen
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Graphic Granite
Graphic Granite (Pegmatite)
igneous
Peridot (Olivine)
Magnesium Iron Silicate (Mg, Fe)2SiO4
mineral
Moqui Marble
Iron Oxide Concretion (Limonite/Hematite shell with Sandstone core)
sedimentary
Vein-filled Sedimentary Rock
Silicified sedimentary rock with quartz/calcite vein
sedimentary
Specular Hematite with Quartz and Limonite
Hematite (Fe2O3) with Quartz (SiO2) and Limonite (FeO(OH)·nH2O)
Mineral
Unidentified polished dark stone with a possible quartz fragment
Indeterminate; appearance may reflect polished basalt, obsidian, or iron-rich rock, with a pale quartz/feldspar inclusion
mineral
Banded River Cobble with Mafic Dike
Hydrothermally altered Graywacke or Sandstone with Mafic Intrusion
igneous and sedimentary
Milky Quartz
Silicon Dioxide (SiO2)
mineral
Reddish-brown, iron-stained rock fragment
Indeterminate; possibly weathered porphyritic volcanic rock
igneous
Small yellow-brown stone, possibly iron-stained quartz or chert
Undetermined; visual evidence is insufficient for a confident identification
mineral
Amygdaloidal Basalt
Amygdaloidal Basalt
igneous
Not a rock
Not a rock
Not a rock
Not a rock
Not a rock
Not a rock
Emerald
Beryl (Be3Al2(SiO3)6)
gemstone
Milky Quartz
Silicon Dioxide (SiO2)
mineral
Unidentified brown stone
Indeterminate from the image; possibly a common iron-stained mineral or rock fragment
mineral
River Pebbles (White Quartz and Basalt mix)
Mixed Clastic Sedimentary Assemblage (SiO2 and Mafic Volcanics)
sedimentary
Quartz
Silicon Dioxide (SiO2)
mineral
Not a rock
Not a rock
Not a rock
Unidentified gray-green stone
Indeterminate; the specimen is too blurred and obscured for reliable identification
mineral
Unknown Rock Specimen
igneous
River Cobble (Quartzite / Sandstone Gravel)
SiO2 (Quartz-rich sedimentary/metamorphic rock)
sedimentary
Small dark tumbled stone, likely black tourmaline
Possibly schorl, NaFe₃Al₆(BO₃)₃Si₆O₁₈(OH)₄; identification uncertain from the image
mineral
Agate (specifically Waterline or Onyx-type Agate)
Silicon Dioxide (SiO2) - variety Chalcedony
mineral
Garnet Schist
Almandine-Mica Schist
metamorphic
Favosites Fossil (Honeycomb Coral)
Favosites sp. (Extinct genus of tabulate coral)
sedimentary
Omarolluk
Omarolluk (Siliceous greywacke with hemispherical voids)
sedimentary
Grass (Organic Matter/Soil)
Poaceae (family of monocotyledonous flowering plants)
Organic Materia (Not a rock or mineral)
Likely rough garnet-bearing rock
Possibly almandine garnet in a metamorphic host; identification is uncertain from the image
metamorphic
Coprolite
Fossilized feces
fossil
Chert Nodule in Limestone
Silicon Dioxide (SiO2) in Calcium Carbonate (CaCO3)
sedimentary
Quartzite River Cobble
Quartzite (SiO2)
metamorphic
Quartz
Silicon Dioxide (SiO2)
mineral
Quartz Geode in Sedimentary Host Rock
Silicon Dioxide (SiO2) in Carbonate Matrix
sedimentary
Small pale mineral fragment, possibly calcite
Unidentified; calcite (CaCO₃) is one possibility
mineral
Botryoidal Agate
Silicon Dioxide (SiO2)
mineral
Painted River Rock
Anthropogenic-modified Siliciclastic Sedimentary Rock
Sedimentary
Small tan stone (undetermined)
Unidentified fine-grained geological material; species cannot be determined from the image
mineral
Fossil coral, likely solitary rugose coral
Rugosa (possibly colonial tabulate coral); calcite/aragonite replaced by calcite
fossil
Quartz Matrix with Iron Staining / Mica Schist
Silicon Dioxide (SiO2) with Iron Oxide staining
mineral
White quartz-rich rock, possibly milky quartz
Likely quartz (SiO₂), though the specimen may be a quartz-rich rock with impurities
mineral