Mineral, Possibly Rock Fragment Containing A Mineral

Basaltic rock fragment (likely vesicular basalt)

Basalt; chiefly plagioclase, pyroxene, and possibly olivine

Vesicular basalt (possibly slag-contaminated)

Basalt; chiefly plagioclase and pyroxene, with possible olivine and secondary minerals

Red jasper (likely)

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

Quartz-rich gravel fragment

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

Possible weathered basalt or iron-rich slag

Basalt, tentatively; composition likely plagioclase and pyroxene with possible magnetite

White tumbled stone, likely quartz or calcite

Indeterminate; possibly quartz (SiO₂) or calcite (CaCO₃)

Polished brown pebble, possibly agate or jasper

Uncertain; likely microcrystalline quartz (SiO₂) if agate/jasper

Tumbled jasper/chert, possibly brecciated jasper

Microcrystalline quartz (SiO₂), with iron-oxide staining and possible chalcedony

Gold-bearing dark rock, possibly magnetite with iron-oxide staining

Likely magnetite (Fe₃O₄) with limonite/goethite; metallic patches may be gold or weathered sulfide, unconfirmed

Quartz-rich rock fragment, possibly milky quartz or quartzite

Quartz (SiO₂), or quartzite if the grains are fused

Sandstone

Arenite (SiO2 principal)

Sodalite with Syenite (Yooperlite)

Sodalite in Syenite (Na8(Al6Si6O24)Cl2)

Amygdaloidal Basalt with Secondary Minerals

Basalt containing secondary mineralization (likely Chlorite, Celadonite, or Zeolites)

Quartz Geode Fragment

Silicon dioxide (SiO2) within a nodule

Unidentifiable Specimen

Undetermined

Weathered granite or granitic gneiss fragment

Quartz–feldspar–mica granite; possibly foliated granitic gneiss

Quartz-rich rock fragment, possibly granite or quartzite

Primarily quartz (SiO₂), with possible feldspar and iron-oxide staining

Unidentified small mineral fragment

Possibly quartz or feldspar-bearing rock; exact identification is uncertain from the image

Quartz-rich rock fragment

Likely milky quartz (SiO₂), possibly a pale quartzite fragment

Weathered greenish rock fragment

Indeterminate; possibly epidote- or chlorite-bearing altered silicate rock

Small brown rock fragment

Undetermined; possibly weathered iron-stained quartzite or chert

Rounded quartz-rich pebble, possibly milky quartz or quartzite

Quartz (SiO₂), or quartzite if the grainy texture is confirmed

Dark metamorphic rock, possibly amphibolite

Amphibolite (tentative; commonly hornblende and plagioclase)

Probable weathered sulfide-bearing rock

Indeterminate; possibly pyrite- or chalcopyrite-bearing matrix

Iron-stained quartz-rich rock (possibly ironstone or ochre-coated quartz)

Undetermined ferruginous rock; yellow-brown coloration likely from goethite and/or limonite (hydrated iron oxides)

Quartz-rich rock fragment, possibly mica-bearing pegmatite

Likely quartz–feldspar–mica aggregate; exact identification requires testing

Sandstone

Arenite (primarily SiO2)

Quartz-rich breccia or vein quartz fragment

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

Small gray metallic-looking rock

Indeterminate; possibly galena-bearing ore or metallic sulfide

Silver-gray metallic ore, possibly galena-bearing rock

Likely galena (PbS) in a host rock, but identification is uncertain from the photograph

Banded agate or jasper fragment

Microcrystalline quartz, SiO₂ (likely iron-stained chalcedony)

Unidentified brown stone

Indeterminate from the image; possibly a common iron-stained mineral or rock fragment

Limestone with Calcite Veins

Sedimentary Calcium Carbonate (CaCO3)

Fossiliferous limestone

Calcitic limestone, predominantly CaCO₃ (often containing fossilized coral or shell fragments)

Sandstone (Ferruginous)

Arenite (Fe-rich)

Quartz-rich river pebble, likely milky quartz

Milky quartz (SiO₂), possibly a quartzite or quartz-rich silicate pebble

Alluvial stream gravel (mixed rock specimens)

Polymictic fluvial deposit; likely mixtures of quartzite, sandstone, shale, chert, basalt, and granite-derived minerals

Granite (likely weathered granitic rock)

Granite; chiefly quartz (SiO₂), feldspar, and mica

Paving-concrete aggregate with a rounded stone

Polymictic gravel aggregate; the central clast appears to be weathered sandstone or volcanic rock

Quartz-rich rock fragment, likely milky quartz with iron staining

Quartz (SiO₂), possibly in a quartz-rich vein rock

Sandstone

Arenite (SiO2 principal)

Basalt with Vesicular Amygdule

Extrusive igneous rock (Mafic)