Sedimentary Or Igneous Fragment

Small rough mineral fragment, possibly quartz or feldspar

Unidentified silicate mineral; image is insufficient for a reliable species identification

Quartz–mica schist or mica-rich quartzite

Quartz with muscovite/biotite mica; likely a quartz-mica schist, possibly pegmatitic

Common Quartz Pebble

Silicon dioxide (SiO2) rock fragment

Weathered iron-rich stone, likely basalt or ironstone

Indeterminate; possibly vesicular basalt (plagioclase–pyroxene) or ferruginous sandstone/ironstone

Unidentified small mineral fragments

Likely quartz- or feldspar-rich material; species cannot be determined reliably from the image

Mixed rock specimens; likely breccia and quartz-bearing rocks

Indeterminate from the image; the brown, angular clasts may be breccia, with white quartz or calcite pieces nearby

Small translucent quartz fragment

Quartz (SiO₂), possibly milky or near-colorless quartz

Quartz Pebble

Silicon Dioxide (SiO2)

Opal

Hydrated Silica (SiO2·nH2O)

Quartz-veined Metamorphic Pebble

Silicate-rich metamorphic rock with quartz veins (SiO2)

Uncertain small stone; possibly weathered quartz-bearing rock

Indeterminate from image; candidate materials include quartz-rich pebble or altered silicate rock

Likely mica schist

Mica-rich schist, probably biotite–quartz–feldspar schist

Weathered rock fragment (likely granite or quartz-rich sandstone)

Uncertain; possible granitic fragment containing quartz and feldspar

Geode

Silicon Dioxide (Quartz/Chalcedony) in carbonate or volcanic host rock

Concrete or asphalt-like aggregate surface with a dark fragment

Uncertain; likely artificial concrete containing mixed lithic aggregate, not a natural rock

Quartz (Milky/Clear Quartz)

Silicon Dioxide (SiO2)

Biotite-rich schist (probable)

Mica schist, likely biotite–quartz–feldspar schist

Milky Quartz

Silicon Dioxide (SiO2)

Clear Quartz

Silicon Dioxide (SiO2)

Fossilized marine shell fragment

Likely a bivalve or gastropod shell preserved as calcite (CaCO₃)

Gneiss

Gneiss

Gneiss

Gneiss

Dark metamorphic rock, likely biotite schist or gneiss

Quartz–feldspar–biotite metamorphic rock; exact identification requires a fresh surface and testing

Small quartz fragment

Quartz (silicon dioxide, SiO₂), possibly milky quartz

Quartz-rich mineral fragment

Quartz (silicon dioxide, SiO₂), possibly milky quartz

Weathered quartz-bearing metamorphic rock, likely gneiss or quartzite

Quartz-rich gneiss/quartzite with feldspar, mica, and iron-oxide alteration

Quartz-bearing metamorphic rock, likely schist or quartzite

Quartz (SiO₂) in a mica-rich metamorphic matrix

Weathered sandstone fragment

Quartz-rich sandstone, likely feldspathic or lithic sandstone

Flint (chert)

Microcrystalline quartz (SiO₂), a variety of chert

Gneiss

Gneiss

Small white quartz fragment

Quartz (silicon dioxide, SiO₂)

Likely raw garnet fragment

Garnet-group silicate, commonly almandine (Fe₃Al₂Si₃O₁₂)

Milky quartz fragment

Quartz (silicon dioxide, SiO₂)

Small translucent quartz fragment

Quartz (SiO₂), identification tentative from the image

Mixed rough mineral specimens, likely quartz-bearing rocks

Probable quartz (SiO₂), with possible feldspar, iron oxides, and altered host rock

Colorless quartz crystal (likely quartz fragment)

Quartz, silicon dioxide (SiO₂)

Milky Quartz

Silicon Dioxide (SiO2)

Small quartz-rich stone, possibly iron-stained quartz or jasper

Quartz (SiO₂), potentially with iron-oxide inclusions

Fossiliferous limestone (reef or shell-rich limestone)

Bioclastic calcarenite/calcirudite; predominantly calcite (CaCO₃)

Quartz Pebble

Silicon Dioxide (SiO2)

Weathered granitic rock

Granite, chiefly quartz + feldspar + mica; possibly a pale granodiorite

Quartz (Milky or Clear fragment)

Silicon Dioxide (SiO2)