All rocks & minerals

Quartz-rich rock, possibly vein quartz in host rock

Quartz (SiO₂), with unidentified host-rock minerals

Likely biotite mica in a host rock

Biotite, a dark mica-group mineral; composition varies, broadly K(Mg,Fe)₃AlSi₃O₁₀(F,OH)₂

Drusy quartz on a matrix (tentative)

Quartz, SiO₂, as a fine-grained drusy coating; associated matrix is unclear from the image

Smoky quartz

Quartz (SiO₂), smoky variety

Probable galena (lead sulfide)

Galena, PbS

Conglomerate

Lithified, poorly sorted gravel and sand; exact mineral composition is not identifiable from the image

Likely iron-stained quartz or quartzite pebbles

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

Quartz-rich rock with dark mica or tourmaline

Likely quartz-mica schist or quartz-rich pegmatitic rock; exact identification is uncertain from the image

Mixed river pebbles, likely including quartz-rich rocks

Unidentified mixed lithologies; the pale pieces appear quartz- or feldspar-rich, but the image is insufficient for a specific identification

Likely mica-rich schist with associated rock fragments

Mica schist, composed mainly of quartz and mica (muscovite and/or biotite); exact identification is uncertain from the image

Mixed stream-worn rocks, likely including quartz-rich gravel

Composition indeterminate; visible material may include quartz (SiO₂) and assorted lithic fragments

Quartz pebble in a coarse mineral-rich rock

Quartz (SiO₂), possibly in a quartz-rich conglomerate or breccia

Likely galena in host rock

Galena (PbS), possibly with quartz or calcite matrix

Pegmatite, probably mica-rich

Granitic pegmatite composed mainly of quartz, feldspar, and mica (likely biotite and/or muscovite)

Likely garnet-bearing metamorphic rock

Garnet schist, possibly garnet-bearing mica schist; garnet is commonly almandine, Fe₃Al₂(SiO₄)₃

Black tourmaline (schorl) in a light-colored host rock

Schorl, NaFe₃Al₆(BO₃)₃Si₆O₁₈(OH)₄

Likely black tourmaline (schorl) in a light-colored host rock

Schorl, NaFe₃Al₆(BO₃)₃Si₆O₁₈(OH)₄; host may be quartz or feldspar

Weathered shale or mudstone

Fine-grained clastic sedimentary rock, predominantly clay minerals and silt-sized quartz

Mixed river gravel (likely alluvial sediment)

Unconsolidated polymictic gravel; rock fragments of varied composition

Conglomerate (pebble-rich rock)

Clastic sedimentary rock composed of rounded pebble- to gravel-sized clasts cemented in a finer matrix

Quartz crystals, likely smoky quartz with iron-stained crystals

Quartz (SiO₂), trigonal crystal system

Fossilized shell (likely an oyster or other bivalve)

Silicified or calcite-preserved bivalve fossil; exact taxon cannot be determined from the image

Dark mafic rock, possibly basalt

Likely basalt; precise identification is uncertain from the image

Likely weathered granite

Granite, a coarse-grained felsic plutonic rock; exact identification is uncertain from the image

Dark, vesicular volcanic rock (likely scoria)

Scoria, a vesicular basaltic to andesitic volcanic rock

Probable amygdaloidal basalt

Basalt, a fine-grained mafic volcanic rock; exact identification is uncertain from the close-up image

Basalt fragments in a light-colored host rock

Basalt (mafic volcanic rock; chiefly plagioclase, pyroxene, and sometimes olivine)

Black tourmaline (schorl) in a light-colored host rock

Schorl, NaFe₃Al₆(BO₃)₃Si₆O₁₈(OH)₄; host appears to be feldspar-rich pegmatite

Black tourmaline (schorl) in light-colored pegmatite

Schorl, NaFe₃Al₆(BO₃)₃Si₆O₁₈(OH)₄, associated with quartz and feldspar

Black tourmaline (schorl) in a light-colored pegmatite matrix

Schorl, NaFe₃Al₆(BO₃)₃Si₆O₁₈(OH)₄

Dark, vesicular volcanic rock (likely basalt or scoria)

Vesicular basalt; exact identification is uncertain from the photograph

Porphyritic basalt

Basalt, likely plagioclase- and pyroxene-bearing

Mica-rich rock, likely biotite schist

Mica schist, composed mainly of biotite and/or muscovite with quartz and feldspar

Ironstone (likely limonite-rich rock)

Limonite, a mixture of hydrated iron oxides; commonly dominated by goethite, α-FeO(OH)

Vesicular volcanic rock (likely scoria)

Scoria, typically basaltic or andesitic volcanic ejecta

Weathered ironstone concretion (tentative)

Iron-oxide-rich concretion, likely goethite/limonite cementing sediment; exact identification requires examination

Porous iron-rich rock or slag-like material

Unidentified; possibly limonite/goethite-rich ironstone

Possible iron-rich sulfide ore fragment

Unidentified sulfide, possibly pyrite-rich material (FeS₂); image is insufficient for a firm identification

Iron-stained rock fragment (possibly limonite/goethite-rich)

Likely limonite, a mixture of hydrated iron oxides; may include goethite (α-FeO(OH))

Weathered iron-rich rock (possibly limonite/goethite-bearing)

Likely limonite, a mixture of iron oxides and hydroxides; exact identification is uncertain from the photo

Granite

Granite, a coarse-grained intrusive felsic igneous rock composed mainly of quartz, feldspar, and mica

Iron-oxide-rich rock fragment (likely limonite/goethite)

Goethite, α-FeO(OH), possibly mixed with limonite and other iron oxides