Mineral, Possibly Rock Fragment Containing A Mineral

Small translucent mineral fragment, possibly quartz

Quartz (SiO₂), tentative identification

Weathered quartz-rich rock, possibly granite or quartzite

Indeterminate; likely quartz–feldspar aggregate (SiO₂ with feldspar minerals)

Sandstone (Weathered Pebble)

Arenite (primarily SiO2)

Red Sandstone

Arenite (Ferruginous Sandstone)

Sandstone Beach Pebble

Clastic Sandstone (SiO2 - Quartz-dominant)

Concretion (likely iron-rich sandstone or claystone concretion)

Diagenetic carbonate/iron-oxide concretion; exact mineralogy requires testing

Brecciated stone pebble

Breccia

Raw quartz-bearing mineral fragment

Quartz, silicon dioxide (SiO₂), possibly included or matrix-bearing

Lichen-covered graywacke or granitic glacial cobble

Indeterminate; likely quartz–feldspar–mica rock, possibly weathered granite or granodiorite

Basalt with Olivine (Peridot)

Basalt containing (Mg,Fe)2SiO4

Conglomerate

Conglomerate (clastic sedimentary rock)

Mica-bearing quartz or feldspar fragment

Likely milky quartz (SiO₂), possibly with biotite/muscovite inclusions; feldspar cannot be excluded visually

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Orange mineral fragment, possibly iron oxide or carnelian

Uncertain; candidates include hematite/goethite (Fe₂O₃/FeO(OH)) or orange chalcedony (SiO₂)

Geode with Quartz and possibly Jasper/Hematite

Quartz (SiO2) and Chalcedony (cryptocrystalline SiO2), possibly stained by iron oxides

Iron-stained quartz or quartz-rich fragment

Quartz (SiO₂), possibly with limonite/goethite staining

Quartz-rich rock, likely milky quartz or quartzite

Quartz (SiO₂), possibly quartzite with iron-oxide staining

Polished red jasper (likely brecciated jasper)

Jasper, microcrystalline quartz/chalcedony (SiO₂), colored mainly by iron oxides

Basalt with Amygdules

Extrusive Igneous Rock (Mafic)

Likely quartz-rich rock fragment

Quartz (silicon dioxide, SiO₂), possibly milky quartz or a quartz-bearing stone

Common Pebble / Sedimentary Rock Fragment

Lithified clastic sediment

Green-brown metamorphic rock, possibly serpentinite

Serpentinite, chiefly serpentine-group minerals (Mg₃Si₂O₅(OH)₄), with possible magnetite, chlorite, or carbonate

Unidentified gray-green rock specimen

Possibly banded gneiss or another foliated metamorphic rock; identification is uncertain from the image

Mica Schist with Quartz

Schist containing Muscovite and Quartz

Fossilized bivalve shell

Fossil Mollusca; likely a cemented or infaunal bivalve, possibly oyster or clam

Possible tektite or dark volcanic rock fragment

Uncertain; likely natural silicate glass (tektite) or basalt

Milky Quartz

Quartz (SiO2)

Small gray granitic rock fragment

Likely granite or granodiorite; quartz–feldspar–mica aggregate

Unidentified purple mineral fragment

Possibly amethyst (quartz), but the image is insufficient for confident identification

Quartz with Iron Staining

Silicon Dioxide (SiO2)

Granite

Intrusive igneous felsic rock

Weathered granite or granitic gneiss fragment

Quartz–feldspar–mica aggregate; likely granite (possibly gneiss)

Orange mineral fragment, possibly citrine or iron-stained quartz

Quartz (SiO₂), tentatively iron-included quartz/citrine

Weathered granite or granodiorite fragment

Granite–granodiorite, chiefly quartz, feldspar, and dark biotite/amphibole

Basalt

Basalt (Mafic volcanic rock)

Small rough quartz crystals, likely quartz/agate fragments

Quartz (SiO₂), possibly chalcedony or included quartz

Quartz with Mica

Silicon Dioxide (SiO2) with Mica group inclusions

Milky quartz-rich rock

Quartz, silicon dioxide (SiO₂), possibly quartzite or a quartz-bearing pegmatite fragment

Unidentified translucent crystal/mineral fragment

Likely quartz (SiO₂), but visual identification is uncertain

Iron-stained quartz-rich rock, possibly quartzite or silicified breccia

Quartz (SiO₂)-dominant rock with iron-oxide minerals, chiefly hematite/goethite

Dark, vesicular volcanic rock (likely basaltic scoria)

Scoria; fine-grained basaltic rock composed chiefly of plagioclase, pyroxene, and possibly olivine

Weathered quartz-rich stone, possibly chalcedony or calcite

Likely microcrystalline quartz (SiO₂) or calcite (CaCO₃); exact identification requires testing