Unknown (Likely Sedimentary Or Metamorphic)

Gneiss

Foliated Metamorphic Gneiss

Weathered sulfide-bearing metamorphic rock (probable pyrite schist)

Quartz–mica schist with iron sulfides, chiefly pyrite (FeS₂), possibly chalcopyrite (CuFeS₂)

Tumbled quartz-rich pebble (likely milky quartz or quartzite)

Quartz, SiO₂; possibly quartzite, a metamorphic quartz aggregate

Mixed mineral and gemstone specimens

Likely amethyst (quartz), malachite, blue calcite or dyed chalcedony, red jasper, and green aventurine/serpentine

Pale green translucent mineral fragment, likely calcite

Calcite (CaCO₃), tentatively; possibly green fluorite or prehnite

Mixed collection of natural stones

Several unidentified lithologies, likely including basalt, granite, quartzite, sandstone, and weathered metamorphic rocks

Mica-rich metamorphic rock, likely biotite schist

Biotite–quartz schist; probable composition of quartz, biotite, feldspar, and minor sulfide or iron-oxide minerals

Weathered quartz-rich rock, possibly quartzite or altered granite

Quartz-dominant silicate rock; exact identification requires a fresh surface and tests

Weathered iron-rich rock, likely shale or slate

Probably ferruginous shale (iron-oxide-stained mudstone); exact identification requires testing

Banded quartz-rich metamorphic rock (likely quartzite or quartz-mica schist)

Quartzite/schist composed chiefly of SiO₂ quartz with mica, feldspar, and iron-oxide or copper-colored accessory minerals

Rounded brown river pebble

Indeterminate; likely weathered sandstone or iron-stained quartzite

Dark gray metamorphic rock fragment

Likely slate or fine-grained schist; mineral composition cannot be confirmed from the image

Pyrite (likely)

Iron disulfide, FeS₂; commonly called fool’s gold

Oyster shell fragment

Ostreidae shell; primarily calcite (CaCO₃)

Garnet (Almandine)

Almandine, Fe3Al2(SiO4)3

River Pebbles (Mixed Lithology)

Conglomerate clasts (Silica-rich and Metamorphic assemblages)

Tumbled quartz-rich pebble

Microcrystalline quartz (SiO₂), possibly milky quartz or chalcedony

Magnetite-rich ironstone (probable magnetite ore)

Magnetite, Fe₃O₄, likely in a fine-grained ironstone matrix

Banded metamorphic rock, likely mica schist

Mica schist, probably muscovite–biotite schist with quartz and feldspar

Pyrite-bearing metamorphic rock (likely schist or quartzite)

Pyrite (FeS₂) in a quartz-rich host rock, possibly mica schist

Small gold-colored mineral crystal, likely pyrite

Pyrite (FeS₂), tentatively; native gold is a less likely alternative

Small brown rock fragment

Undetermined; possibly weathered iron-stained quartzite or chert

Mixed rock and mineral specimen collection

Varied silicate, carbonate, and oxide minerals; individual identification is not possible from this group photograph

Quartz Pebble

Silicon Dioxide (SiO2)

Banded gneiss

Quartzo-feldspathic biotite gneiss, possibly garnet-bearing

Dark metamorphic cobble, likely slate or phyllite

Foliated metamorphic rock, probably carbonaceous slate/phyllite; exact identification requires testing

Likely weathered chert or siliceous shale

Cryptocrystalline quartz (SiO₂), possibly with clay minerals

Metallic sulfide-rich rock, possibly pyrite-bearing schist or marcasite specimen

Likely pyrite (FeS₂) in a foliated host rock; exact identification requires testing

Quartz-rich mica schist (probable)

Mica–quartz schist; mainly quartz (SiO₂) with muscovite/biotite mica and possibly feldspar

Quartz (Milky/Common)

Silicon Dioxide (SiO2)

Weathered quartz-rich cobble (likely quartzite or siliceous sandstone)

Quartzite, predominantly SiO₂; exact identification requires testing

Biotite schist with quartz veins

Quartz–mica schist; primarily quartz (SiO₂), biotite mica, and feldspar

Rounded metamorphic pebble, likely mica schist or gneiss

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

Quartz vein in foliated metamorphic rock

Likely quartz-bearing schist or gneiss; visible crystal is quartz (SiO₂)

Polished gemstone tower assortment

Primarily quartz varieties and simulants; apparent amethyst (SiO₂), rose quartz (SiO₂), clear quartz (SiO₂), fluorite (CaF₂), sodalite, malachite, and possibly dyed or composite stones

Sandstone (Arkose)

Arkose Sandstone (SiO2 with KAlSi3O8)

Hard Sandstone (Quartzite)

Quartz-rich Sedimentary Rock (Proto-Quartzite)

Likely limestone or marble fragment

Calcite-rich carbonate rock; possibly marble (CaCO₃)

Likely slate or fine-grained metamorphic rock

Slate; predominantly microcrystalline quartz, mica, and clay minerals

Quartz-rich sandstone or quartzite pebble

Granular quartz (SiO₂), possibly with minor feldspar or carbonate cement

Likely limestone or marble

Calcite-rich carbonate rock; chiefly calcium carbonate, CaCO₃

Quartz (Milky Variant)

Quartz (Silicon Dioxide, SiO2)