Unknown (Likely Sedimentary Or Metamorphic)

Tumbled quartz-rich pebble, likely quartzite or chert

Quartz (SiO₂), possibly quartzite; exact identification is uncertain from the image

Rounded brown river pebble

Indeterminate; likely weathered sandstone or iron-stained quartzite

Mica-rich metamorphic rock, likely biotite schist

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

Likely weathered limestone or marble fragment

Calcite-rich carbonate rock; likely limestone (CaCO₃), possibly recrystallized marble

Tumbled quartz-rich rock, possibly calcite or sandstone

Indeterminate from photograph; likely microcrystalline quartz (SiO₂) or calcite (CaCO₃)

Likely magnetite-rich rock fragment

Magnetite (Fe₃O₄), possibly in a fine-grained host rock

Small pale stone, likely quartzite or limestone fragment

Indeterminate; possible quartzite (mostly SiO₂) or calcitic limestone (CaCO₃)

Pyrite-bearing metamorphic rock (likely schist or quartzite)

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

Biotite-rich mica schist

Mica schist, likely containing biotite and quartz with possible feldspar

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

Banded gneiss

Quartzo-feldspathic biotite gneiss, possibly garnet-bearing

Red Jasper

Jasper (Silicon Dioxide with Iron Oxide inclusions, SiO2)

Blue apatite (likely dyed or enhanced)

Apatite group; fluorapatite, Ca5(PO4)3F, is the common blue variety

River Pebbles (Mixed Lithology)

Conglomerate clasts (Silica-rich and Metamorphic assemblages)

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

Garnet-bearing schist (likely)

Garnet mica schist, with almandine garnet (Fe₃Al₂(SiO₄)₃) likely

Garnet (Almandine)

Almandine, Fe3Al2(SiO4)3

Hard Sandstone (Quartzite)

Quartz-rich Sedimentary Rock (Proto-Quartzite)

Pyrite (likely)

Iron disulfide, FeS₂; commonly called fool’s gold

Banded gneiss pebble

Gneiss, a foliated metamorphic rock, likely quartz–feldspar–mica gneiss

Dark gray metamorphic rock fragment

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

Tumbled quartz-rich pebble

Microcrystalline quartz (SiO₂), possibly milky quartz or chalcedony

Mica-rich schist (probable)

Mica schist, likely muscovite–biotite schist; exact identification requires examination or testing

Likely weathered chert or siliceous shale

Cryptocrystalline quartz (SiO₂), possibly with clay minerals

Likely limestone or marble

Calcite-rich carbonate rock; chiefly calcium carbonate, CaCO₃

Likely milky quartz fragment

Quartz (silicon dioxide, SiO₂)

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

Quartzite, predominantly SiO₂; exact identification requires testing

Likely graywacke (feldspathic sandstone)

Lithified sandstone, likely a feldspathic or lithic wacke; exact identification requires closer examination

Hematite (likely Botryoidal or Specularite variant)

Iron(III) oxide (Fe2O3)

Banded metamorphic rock, likely mica schist

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

Green calcite (probable)

Calcite, calcium carbonate (CaCO₃)

Foliated Metamorphic Rock (likely Gneiss or Schist)

Gneissic Metamorphic Rock

Likely foliated metamorphic rock, possibly schist

Mica schist or micaceous quartzite; exact identification is uncertain from the photograph

Likely graphite-rich metamorphic rock (graphitic schist)

Graphitic schist; chiefly carbon (graphite) with quartz, mica, and possibly sulfides

Likely slate or fine-grained metamorphic rock

Slate; predominantly microcrystalline quartz, mica, and clay minerals

Feldspathic Gneiss

High-grade Metamorphic Rock (Gneiss)

Pebble (likely Quartz or Chert)

SiO₂ (Silicon Dioxide) - referring to the likely main mineral composition, Quartz. If it's chert, the scientific name remains SiO₂ with a microcrystalline structure.

Quartz vein in host rock

Quartz (SiO₂), with possible feldspar or carbonate-bearing matrix

Banded metamorphic rock, likely gneiss or banded amphibolite

Quartz–feldspar–biotite gneiss or amphibolite; exact identification requires thin-section or mineral tests