All rocks & minerals

Tumbled orange-brown gemstone, likely carnelian

Carnelian (orange chalcedony, microcrystalline quartz; SiO₂)

Red jasper pebble

Jasper, an opaque microcrystalline variety of quartz (SiO₂), colored mainly by iron oxides

Quartz-rich pegmatite (likely milky quartz with feldspar)

Granitic pegmatite, composed mainly of quartz (SiO₂) and feldspars

Polished common opal

Opal, hydrated amorphous silica (SiO₂·nH₂O)

Clear calcite (optical calcite)

Calcite, CaCO₃

Foliated metamorphic rock, likely schist

Mica schist (likely quartz–mica schist; exact identification requires closer examination)

Dyed agate slice

Microcrystalline quartz (SiO₂), commonly chalcedony; blue color appears artificially dyed

Rounded greenish-gray pebble, likely quartzite

Quartzite (mostly crystalline quartz, SiO₂); identification is provisional from the image

Orbicular jasper (likely)

Silicified, iron-rich volcanic rock with orbicular structures; exact mineralogy cannot be confirmed from the image

Light-colored rounded pebble, likely quartzite

Quartzite, composed predominantly of quartz (SiO₂); identification is tentative from the image

Porous fossil coral fragment

Fossilized colonial coral; precise taxon cannot be determined from the image

Rounded beach or river pebble

Unidentified fine-grained rock; composition cannot be determined from the image

Small pale-gray stone, likely a water-worn quartzite or chert pebble

Undetermined; possibly quartzite (predominantly SiO₂)

Small pale stone pebble, likely limestone

Likely calcite-rich limestone (CaCO₃); exact identification is uncertain from the image alone

Weathered, iron-stained rock pebble

Indeterminate; possibly iron-oxide-cemented sandstone or laterite

Weathered granite or granitic gneiss

Quartz–feldspar–mica rock; likely granite, possibly gneiss

Likely waterworn jasper or chert pebble

Microcrystalline quartz (chalcedony), SiO₂

Polished agate (likely moss or plume agate)

Microcrystalline quartz, SiO₂; chalcedony with brown iron-oxide inclusions

Red jasper (likely tumbled)

Jasper, an opaque microcrystalline variety of quartz (SiO₂), colored red by iron oxides

Weathered, quartz-rich rock (possibly quartzite)

Quartzite, composed predominantly of quartz (SiO₂); identification is uncertain from the photo

Weathered, pyrite-bearing shale

Clay-rich shale, possibly containing pyrite (FeS₂) and quartz

Weathered granite

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

Weathered light-colored rock fragment, possibly quartz-rich rock

Undetermined; appearance may be quartzite or a quartz-rich granite fragment

Weathered, foliated metamorphic rock (likely schist)

Mica schist, composition uncertain from the photograph

Polished amethyst

Quartz, SiO₂; purple variety colored by trace iron and irradiation

Dalmatian jasper (Dalmatian stone)

Commercially called Dalmatian jasper; typically a feldspar-rich rock with dark arfvedsonite or tourmaline-group inclusions, rather than true jasper

Polished agate (likely banded/chalcedony agate)

Microcrystalline quartz, SiO₂; agate variety of chalcedony

Tumbled tiger’s eye

Quartz variety with chatoyant fibrous inclusions, commonly pseudomorphs after crocidolite (riebeckite)

Pink-purple mica-bearing rock, likely lepidolite-rich pegmatite

Lepidolite (K(Li,Al)₃(Al,Si,Rb)₄O₁₀(F,OH)₂), likely with quartz and feldspar

Dark, coarse-grained rock; likely gabbro or diorite

Undetermined mafic-to-intermediate intrusive igneous rock; exact identification requires closer examination

Honey-colored calcite on dark matrix

Calcite (CaCO₃), likely with an unidentified host-rock matrix

Likely blue-gray fluorite

Fluorite (calcium fluoride, CaF₂)

Smoky quartz crystal cluster

Quartz (SiO₂), smoky variety

Amazonite-bearing pegmatite

Amazonite (green microcline feldspar, KAlSi₃O₈) in a quartz- and mica-rich pegmatite

Quartz vein in host rock

Quartz (SiO₂) in an undetermined mineralized host rock

Quartz geode with druzy crystals

Quartz (SiO₂), likely with iron-oxide staining and darker host rock

Gypsum (selenite)

Gypsum, CaSO₄·2H₂O; crystalline variety commonly called selenite

Likely selenite (transparent gypsum) crystal cluster

Gypsum, CaSO₄·2H₂O; selenite is its clear crystalline variety

Likely green-schist specimen

Greenschist, a chlorite–epidote–actinolite-bearing metamorphic rock

Tourmalinated quartz point

Quartz (SiO₂) containing black tourmaline, usually schorl (NaFe₃Al₆(BO₃)₃Si₆O₁₈(OH)₄)

Likely calcite-rich limestone

Calcite (CaCO₃) in micritic or crystalline limestone; identification from the image is provisional

Likely basalt or other fine-grained volcanic rock

Indeterminate dark mafic volcanic rock; commonly basalt, composed mainly of plagioclase and pyroxene, often with olivine