Unknown (Likely Sedimentary Or Metamorphic)

Biotite-rich gneiss

Gneiss, likely quartz–feldspar–biotite gneiss

Tumbled banded quartzite or jasper

Silica-rich quartzite; likely iron-oxide-stained quartz (SiO₂)

Yellow Agate

Agate (Varietal form of Chalcedony/Quartz, SiO2)

Likely weathered metamorphic rock (quartzite or schist)

Quartz-rich foliated metamorphic rock; exact identification requires testing

Banded gneiss pebble

Gneiss, commonly quartz–feldspar–mica gneiss

Pyrite-bearing rock

Likely pyrite (FeS₂), possibly with quartz or other sulfide minerals

Probable mica schist

Schist, likely muscovite–biotite schist

Greenish Metamorphic Rock (likely containing epidote or chlorite)

Metamorphic rock, possibly epidosite or greenstone

Beach Pebbles and Quartz Aggregates

Quartz pebbles and biogenic fragments (SiO2, CaCO3)

Likely biotite-rich schist

Mica schist, composed chiefly of biotite and quartz; exact identification is uncertain from the image.

Specular Hematite with Quartz and Limonite

Hematite (Fe2O3) with Quartz (SiO2) and Limonite (FeO(OH)·nH2O)

Weathered brown river pebble, likely sandstone or iron-rich quartzite

Indeterminate; probable quartz-rich sandstone (quartz and iron-oxide cement)

Quartz pebble

Silicon dioxide (SiO2)

Carved Mottled Greenish-Yellow Crystal/Glass Object

Unknown; possibly a form of quartz (chalcedony/jadeite/nephrite) or glass/resin.

Probable fossilized bone fragment

Fossil bone; taxonomic identity and age cannot be determined from the image

Pyrite (likely)

Pyrite, FeS₂

Likely biotite mica schist

Mica schist, chiefly biotite (K(Mg,Fe)₃AlSi₃O₁₀(F,OH)₂) with quartz and feldspar

Gneiss

Gneiss

Foliated metamorphic cobble, likely gneiss

Biotite–quartz–feldspar gneiss (tentative)

Weathered mica-rich metamorphic rock, likely schist

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

Polished operculum (“Shiva eye” shell)

Calcium-carbonate shell operculum, commonly from a turban snail (family Turbinidae); not a mineral specimen

Garnet (likely Almandine)

Almandine (Fe3Al2(SiO4)3)

Quartz fragment

Quartz (silicon dioxide, SiO₂)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Likely calcite

Calcite, calcium carbonate (CaCO₃)

Mica-bearing metamorphic rock with a dark mica crystal

Likely schist or mica-rich gneiss; dark crystal appears to be biotite, though identification from the photo is uncertain

Dark gray metamorphic rock, likely hornfels or fine-grained amphibolite

Hornfels/amphibolite; commonly quartz, feldspar, amphibole, biotite, and minor sulfides

Granitic Gneiss

Gneiss (containing Potassium Feldspar and Quartz)

Dark metamorphic rock, likely biotite schist or hornblende-bearing gneiss

Probable mica schist/amphibolite; composition may include biotite, amphibole, quartz, feldspar, and iron oxides

Likely garnet-bearing rock

Garnet-rich schist or garnetiferous metamorphic rock; garnet is commonly almandine, Fe₃Al₂(SiO₄)₃

Quartz (Small Fragment)

Silicon Dioxide (SiO2)

Red Jasper (Quartzite)

Silicon Dioxide (SiO2) with iron oxide inclusions

Tumbled quartz-rich carbonate rock

Likely massive quartz (SiO₂), possibly calcite-bearing marble or limestone

Rounded gray river pebble, likely fine-grained basalt or andesite

Basaltic-andesitic volcanic rock; commonly plagioclase feldspar, pyroxene, and minor iron oxides

Rounded greenish river pebble

Indeterminate; possibly weathered greenstone, basalt, or serpentinized ultramafic rock

Weathered quartz-rich rock, likely chert or quartzite

Microcrystalline quartz (SiO₂), possibly with iron-oxide staining

Likely mica schist

Mica-rich schist, probably muscovite–quartz schist

Faceted clear gemstone, likely glass or cubic zirconia

Undetermined; could be synthetic cubic zirconia (ZrO₂) or cut glass (silica-based)

Pyrite-bearing sulfide specimen

Pyrite (FeS₂), possibly mixed with chalcopyrite or other iron sulfides

Rounded orange-brown pebble (likely iron-stained quartzite)

Quartz-rich quartzite; exact identification is uncertain from the image

Polished granitic pebble

Granite, composed chiefly of quartz, feldspar, and mica/amphibole

Yellow chalcedony or quartz fragment

Microcrystalline quartz, SiO₂ (tentative; possibly iron-stained chalcedony)