Mineral, Possibly Rock Fragment Containing A Mineral

Sandstone (with Limonite staining)

Arenite (primarily SiO2 with FeO(OH)·nH2O)

Dark tumbled mineral/rock fragment (tentatively hematite-rich material)

Likely hematite (Fe₂O₃), possibly magnetite-bearing ironstone

Weathered conglomeratic breccia

Polymictic conglomerate/breccia, likely iron-stained

Rounded quartz-rich pebble, possibly milky quartz or quartzite

Quartz (SiO₂), potentially quartzite if recrystallized rock

Fossiliferous limestone concretion

Calcite-rich limestone (primarily CaCO₃), possibly containing a fossil shell or coral fragment

Serpentine-rich rock (possibly lizardite/serpentinite)

Serpentinite, composed chiefly of serpentine-group minerals such as lizardite, antigorite, or chrysotile

Likely weathered quartz-rich rock fragment

Uncertain; possibly quartz-bearing granitic or metamorphic material (SiO₂-dominant)

Small dark rock fragment

Uncertain; possibly weathered basalt or slag

Granite

Intrusive Igneous Rock

Granite fragment

Granite (Felsic Plutonic Rock)

Weathered brown rock fragment

Indeterminate; possibly weathered granite, gneiss, or iron-stained quartz-rich rock

Conglomerate

Conglomerate (SiO2 matrix with various silicate clasts)

Vesicular basalt (possibly scoriaceous basalt)

Basalt; chiefly plagioclase, pyroxene, and olivine, with iron oxides

Unidentified translucent mineral fragment, possibly quartz

Likely quartz (SiO₂), though the photograph is insufficient for confident identification

Likely metallic sulfide mineral fragment

Possibly galena (PbS) or pyrite (FeS₂); identification is uncertain from the photograph

Rounded greenish-gold rock or mineral pebble

Indeterminate; possibly serpentine-rich stone, weathered sulfide, or iron-stained metamorphic rock

Unidentified small rounded mineral/rock fragment

Indeterminate from image; possibly quartz or chalcedony with iron-oxide staining

Likely weathered limestone

Calcite-rich limestone (mostly CaCO₃), possibly dolomitic limestone

Weathered granite fragment

Granite, predominantly quartz–feldspar–mica rock

Unidentified polished green mineral specimen

Possibly aventurine quartz or serpentine; image insufficient for definitive identification

Peridotite (Olivine Rock)

Peridotite (composed largely of olivine, (Mg, Fe)2SiO4)

Likely weathered quartz-rich rock fragment

Indeterminate; possibly quartz-bearing sandstone or chert with iron-oxide staining

Shale

Argillite / Shale

Sandstone (likely Ferruginous)

Arenite (SiO2 with iron oxide impurities)

Milky quartz fragment

Quartz, silicon dioxide (SiO₂)

Mica-bearing metamorphic rock, likely schist

Muscovite–biotite schist, possibly phyllite

Dark metallic sulfide specimen, possibly galena

Galena (lead sulfide, PbS), identification tentative

Weathered quartz-rich pebble, possibly granite or pegmatite

Quartz (SiO₂) with probable feldspar and minor mica/iron-oxide inclusions

Weathered quartz-rich pebble (tentative)

Likely quartz/chalcedony, SiO₂, possibly iron-stained

Likely iron-stained quartz or quartz-rich rock fragment

Quartz (SiO₂), possibly colored by iron oxides such as goethite or hematite

Biotite-rich granite or granitic gneiss

Quartz–feldspar–biotite granite; possibly foliated granitic gneiss

Quartz-rich stone, possibly calcite or quartz

Likely quartz (SiO₂) or calcite (CaCO₃); exact identification requires testing

Quartz-rich pebble (likely milky quartz)

Quartz, silicon dioxide (SiO₂), possibly a weathered quartzite fragment

Sandstone

Arenite (SiO2 primarily)

Sandstone

Arenite

Sandstone

Arenite (SiO2 based typically)

Weathered tan mineral/rock fragment

Indeterminate from image; possibly iron-stained quartz, feldspar-rich rock, or limonite-bearing material

Weathered iron-rich rock, possibly laterite or limonite-bearing stone

Hydrated iron oxides/hydroxides, chiefly limonite-goethite mixture; exact identification requires testing

Likely galena-bearing sulfide fragment

Galena (PbS), possibly mixed with sphalerite and/or chalcopyrite

Quartz-rich pale rock fragment

Likely milky quartz (SiO₂), possibly quartzite

Quartz-rich rock fragment (tentative)

Quartz, silicon dioxide (SiO₂), possibly in a weathered host rock

Weathered quartz-rich rock, possibly granite or quartzite

Likely quartz–feldspar aggregate; precise identification requires testing