Uncertain

Likely weathered mica schist fragment

Mica schist, chiefly muscovite/biotite mica with quartz and feldspar

Iron-rich flint or chert fragment

Microcrystalline quartz (SiO₂), likely ferruginous chert

Tumbled dark stone, likely basalt or basaltic rock

Fine-grained mafic volcanic rock; commonly basalt, composed chiefly of plagioclase and pyroxene with possible olivine and iron oxides

Likely weathered iron-rich stone

Uncertain; possibly limonite/goethite-bearing rock

Quartz-rich gravel fragment

Quartz (silicon dioxide, SiO₂), possibly with feldspar or carbonate inclusions

Likely weathered basalt or mafic volcanic rock

Basalt; chiefly plagioclase feldspar, pyroxene, and possibly olivine

Tumbled, weathered limestone or calcareous concretion

Calcite-rich limestone; predominantly calcium carbonate (CaCO₃)

Likely milky quartz with iron-oxide inclusions

Quartz, silicon dioxide (SiO₂)

Purple fluorite specimen

Fluorite (calcium fluoride, CaF₂)

Uncertain small pale mineral fragment

Indeterminate; possibly calcite or a light-colored feldspar fragment

Agatized fossil fragment, possibly silicified coral

Chalcedony (microcrystalline SiO₂) replacing carbonate fossil material

Polished copper-bearing mineral specimen, likely malachite-rich copper ore

Malachite, Cu₂CO₃(OH)₂, possibly mixed with chrysocolla or limonite

Blue-green copper mineral specimen, likely chrysocolla or turquoise

Probable chrysocolla, hydrated copper phyllosilicate (Cu₂H₂Si₂O₅(OH)₄·nH₂O); turquoise, CuAl₆(PO₄)₄(OH)₈·4H₂O, is an alternative

Likely petrified wood or silicified fossil fragment

Silicified wood; predominantly microcrystalline quartz (SiO₂)

Weathered granite (likely with accessory quartz)

Granite; chiefly quartz, K-feldspar, plagioclase, and biotite/hornblende

Rough turquoise-bearing rock (probable turquoise matrix)

Turquoise, CuAl₆(PO₄)₄(OH)₈·4H₂O, likely in a host-rock matrix

Gabbro or coarse-grained dioritic rock

Plutonic mafic/intermediate rock; typically plagioclase feldspar + pyroxene ± amphibole/biotite

Coarse-grained mica-bearing metamorphic rock, likely schist

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

White quartz in dark matrix (likely quartz-bearing breccia or polished composite specimen)

Quartz, SiO₂, in an unidentified dark silicate matrix

Tumbled black stone, likely black obsidian

Obsidian — natural volcanic glass, primarily SiO₂

Red jasper / iron-rich chert

Microcrystalline quartz (SiO₂) colored by hematite/goethite

Possible tektite or volcanic glass specimen

Natural silica glass; composition commonly near SiO₂, but exact identification requires chemical testing

Pink-and-gray quartz-rich pegmatite, possibly rose quartz with feldspar

Quartz (SiO₂) with K-feldspar/plagioclase; likely pegmatitic granite

Polished ocean jasper (orbicular jasper), probable

Microcrystalline quartz (SiO₂), chiefly chalcedony with iron-oxide and other mineral inclusions

Red cabochon gemstone, likely carnelian

Carnelian: orange-red chalcedony, microcrystalline quartz (SiO₂)

Weathered granite or granitic gneiss cobble

Granite; primarily quartz, feldspar, and mica

Tumbled yellow jasper or petrified wood fragment

Microcrystalline quartz (chalcedony), SiO₂, possibly iron-oxide-bearing jasper

Tumbled serpentine (likely)

Serpentine-group minerals, commonly lizardite or antigorite; approximate composition Mg₃Si₂O₅(OH)₄

Blue quartzite or blue aventurine glass-like aggregate

Quartzite, predominantly SiO₂ (identification uncertain from image)

Weathered quartz-rich cobble, possibly quartzite or feldspar-rich granite

Quartz–feldspar aggregate; identification is uncertain from the photograph

Iron meteorite fragment (likely weathered meteorite)

Fe–Ni metal, commonly kamacite with taenite; possible stony-iron or iron-oxide fusion crust

Metallic sulfide ore, likely pyrite-bearing rock

Pyrite (FeS₂), possibly with marcasite or other sulfides

Weathered amphibolite or mafic metamorphic rock

Amphibolite; chiefly hornblende amphibole and plagioclase feldspar

Possible tektite or dark volcanic rock fragment

Uncertain; likely natural silicate glass (tektite) or basalt

Tumbled tan pebble, likely sandstone or chert

Uncertain; probable quartz-rich sandstone (SiO₂-bearing)

Likely weathered gray stone or chert fragment

Uncertain; possibly microcrystalline quartz (SiO₂)-rich chert

Migmatitic gneiss

Felsic banded gneiss, commonly quartz–feldspar–biotite ± amphibole

Tumbled yellow chalcedony (likely citrine or yellow jasper)

Microcrystalline quartz, SiO₂; exact identification is uncertain from the photograph

Likely blue glass or synthetic gemstone jewelry

Uncertain; possibly synthetic spinel, cubic zirconia, or blue glass

Weathered iron-rich rock, possibly meteorite

Uncertain; likely goethite/hematite-rich material, with meteorite possibility

Weathered quartz-rich rock, possibly granite or pegmatite fragment

Uncertain; likely quartz–feldspar aggregate, potentially granitic pegmatite

Possible tektite or iron-rich slag-like natural specimen

Uncertain; possibly natural glass (tektite) or magnetite-rich rock