Sedimentary Or Igneous

Biotite-rich schist (mica schist)

Mica schist, chiefly biotite (K(Mg,Fe)₃AlSi₃O₁₀(OH,F)₂), with possible quartz and feldspar

Weathered schist or gneiss

Quartz–feldspar–mica metamorphic rock

Gneiss

Gneissic Metamorphic Rock

Tumbled green aventurine

Quartzite dominated by quartz (SiO₂), commonly containing fuchsite mica or chlorite

Weathered, quartz-rich metamorphic rock (likely schist or gneiss)

Quartz–feldspar–mica schist/gneiss, with surface lichens and iron-oxide staining

Likely quartz fragment

Quartz (silicon dioxide, SiO₂)

Garnet-bearing gneiss

Biotite–garnet gneiss, typically quartz + feldspar + biotite + almandine garnet

Red Jasper

Silicon Dioxide (SiO2) with iron oxide inclusions

Weathered schist or gneiss cobble

Foliated silicate rock, likely mica schist or biotite gneiss

Gneiss

Gneiss

Dark metamorphic rock, likely biotite schist or gneiss

Quartz–feldspar–biotite metamorphic rock; exact identification requires a fresh surface and testing

Likely garnet-bearing schist or gneiss

Mica schist/gneiss containing quartz, feldspar, mica, and probable almandine garnet

Weathered schist or gneiss boulder

Micaceous quartz-feldspar schist/gneiss; exact identification is limited by the photograph

River Stone (Chalcedony/Jasper variety)

Microcrystalline Quartz (SiO2)

Weathered quartz-mica schist

Quartz–muscovite/biotite schist, locally iron-oxide stained

Likely weathered schist or gneiss fragment

Micaceous quartz-feldspar metamorphic rock; exact identification requires testing

Banded Gneiss / Metamorphic River Pebble

Gneiss (Foliated Metamorphic Rock)

Rounded metamorphic pebble, likely mica schist or gneiss

Mica schist/gneiss; commonly quartz, feldspar, and biotite or muscovite mica

Gneiss (Gneissic Granite Pebble)

Metamorphic rock rich in Quartz, Feldspar, and Mica

Red Jasper

Silicon Dioxide with Iron Oxide inclusions (SiO2)

Quartz-bearing metamorphic rock, likely schist or quartzite

Quartz (SiO₂) in a mica-rich metamorphic matrix

Biotite-bearing gneiss or schist

Quartz–feldspar–mica metamorphic rock, likely mica schist/gneiss

Silver-colored mica schist

Muscovite–quartz schist, possibly with biotite

Quartz–mica schist or mica-rich quartzite

Quartz with muscovite/biotite mica; likely a quartz-mica schist, possibly pegmatitic

River Pebble (Gneiss / Granitic Schist)

Metamorphic Rock (Quartz-Feldspar-Mica assembly)

Weathered metamorphic rock, possibly schist or gneiss

Indeterminate; likely quartz–feldspar–mica rock, potentially greenschist or gneiss

Green Fluorite

Fluorite (Calcium Fluoride, CaF2)

Biotite mica schist (probable)

Schist dominated by biotite mica; commonly quartz–feldspar–biotite

Weathered metamorphic rock, likely mica schist or gneiss

Quartz–feldspar–mica schist/gneiss; exact identification is uncertain from the photograph

Tourmaline-rich schist (likely black tourmaline)

Schist containing schorl, Fe-rich NaFe3Al6(BO3)3Si6O18(OH)4

Red Jasper

Silicon Dioxide (SiO2) with Hematite inclusions

Pyrite-bearing schist or quartzite

Micaceous quartz-rich metamorphic rock with pyrite (FeS₂)

Mica-bearing metamorphic rock, likely schist

Muscovite/biotite mica schist with quartz and feldspar

Jasper

Jasper (Silicon Dioxide, SiO2 plus iron oxide impurities)

Weathered quartz-bearing metamorphic rock

Likely quartz–feldspar schist or gneiss, possibly with iron-oxide alteration

Likely raw mica-bearing metamorphic rock or mineral fragment

Tentatively biotite schist; visually similar dark mica-rich material

Mixed rock and mineral specimen collection

Mostly undetermined from the photograph; apparent quartz-rich rocks, sandstone, granite/gneiss, and possibly iron-oxide-bearing specimens

Likely foliated metamorphic rock (quartz-mica schist or gneiss)

Quartz–feldspar–mica metamorphic rock; exact identification requires a fresh surface and tests

Garnet-bearing metamorphic rock, likely garnet schist or amphibolite

Almandine garnet (Fe₃Al₂Si₃O₁₂) in mica- or amphibole-rich matrix

Banded metamorphic river cobble, likely gneiss or metasedimentary rock

Quartz–feldspar–mica gneiss or quartzite with cross-cutting quartz veins

Raw garnet-rich metamorphic rock

Likely garnet-bearing schist or garnetite; garnet-group silicates, commonly almandine (Fe₃Al₂Si₃O₁₂)

Fluorite

Fluorite (Calcium Fluoride, CaF2)