Mineral, Possibly Rock Fragment Containing A Mineral

Red Sandstone

Arenite (Ferruginous Sandstone)

Dark gray fine-grained stone, likely basalt or andesite

Basalt–andesite volcanic rock; commonly composed of plagioclase, pyroxene, and possibly olivine or magnetite

Weathered igneous rock fragment, possibly granite or granitic gneiss

Indeterminate; likely quartz–feldspar–mica aggregate (granite), possibly foliated gneiss

Gabbro

Basaltic Plutonic Rock (Gabbro)

Fine-grained green-gray rock pebble, likely basalt or greenstone

Probable basalt (plagioclase and pyroxene), possibly altered to greenstone

Conglomerate

Conglomerate (Clastic Sedimentary Rock)

Sandstone (with Chert/Quartzite)

Arenite (primarily SiO2)

Rounded gray-green pebble, likely basaltic or metamorphic

Indeterminate mafic rock; possibly basalt, diabase, or greenstone

Conglomeratic concrete or asphalt aggregate surface with dark bituminous chunks

Polymictic gravel aggregate; dark pieces likely bitumen/asphalt, not a natural rock

Iron-rich breccia or weathered ironstone

Hematite/goethite-bearing breccia; exact identification requires testing

Granite

Intrusive igneous rock

Dark mafic rock, possibly basalt with weathered iron staining

Likely basalt; exact identification is uncertain from the photograph

Weathered quartz-rich rock fragment

Indeterminate; possibly weathered granite, quartzite, or rhyolite

Dark gray crystalline rock, possibly basalt

Basalt (tentative; plagioclase–pyroxene–iron oxide assemblage)

Small dark mineral fragment

Undetermined; image lacks diagnostic detail for reliable identification

Painted Rock / Geode Specimen

Silicon Dioxide with artificial pigment coating

Green glassy mineral fragment, possibly fluorite

Fluorite (calcium fluoride, CaF₂), tentative identification

Greenish translucent mineral fragment

Indeterminate; possibly serpentine, epidote, or green glassy feldspar

Weathered quartz-rich pegmatite, likely feldspar/quartz

Granitic pegmatite; chiefly microcline or plagioclase feldspar (KAlSi₃O₈–NaAlSi₃O₈) with quartz (SiO₂), possibly mica

Chrysoprase (green chalcedony), likely rough fragment

Chalcedony, microcrystalline quartz (SiO₂), colored green primarily by nickel-bearing inclusions

Quartz-rich rock, possibly milky quartz in a weathered host

Quartz (SiO₂); the specimen may be a quartz vein fragment, but the image is insufficient for a precise identification

Metamorphosed mafic rock, likely amphibolite

Amphibolite, chiefly hornblende + plagioclase; possibly mafic gneiss or altered basalt

Shale

Sedimentary rock composed of clay minerals and quartz

Rounded quartz-veined pebble

Likely quartz-veined metamorphic rock; exact host rock is indeterminate from the image

Small pale stone, possibly quartz or limestone

Indeterminate from image; likely quartz (SiO₂) or calcite-rich limestone (CaCO₃)

Pink chalcedony (likely rough agate/chalcedony)

Microcrystalline quartz, SiO₂; chalcedony variety, possibly iron-bearing

Sandstone (Quartz-rich)

Clastic sedimentary rock (SiO2 primary)

Blue glassy mineral fragment, possibly sodalite or dyed/cobalt glass

Uncertain; likely sodalite (Na₈Al₆Si₆O₂₄Cl₂) if natural, but vivid blue color may indicate cobalt-colored glass

Weathered granite or granitic gneiss

Quartz–feldspar–mica granite; possibly weakly foliated granitic gneiss

Likely granitic rock fragment

Granite or granodiorite; quartz–feldspar–mica aggregate

Bivalve Fossil (Clam)

Class Bivalvia (e.g., Exogyra or Gryphaea species)

Granite-like rock

Coarse-grained felsic intrusive rock; likely granite or granodiorite

Quartz-rich rock fragment

Unidentified quartz–feldspar-rich rock; exact lithology cannot be determined from the image

Rose quartz

Quartz (SiO₂), pink variety

Metallic sulfide ore, likely pyrite-bearing rock

Pyrite (FeS₂), possibly with marcasite or other sulfides

Tumbled blue stone, likely sodalite

Sodalite (Na₈Al₆Si₆O₂₄Cl₂), possibly blue calcite or dyed quartz

Amygdaloidal Basalt

Amygdaloidal Basalt (Mafic volcanic rock)

Turquoise

Hydrated phosphate of copper and aluminium (CuAl6(PO4)4(OH)8·4H2O)

Sandstone

Clastic sedimentary rock (primarily SiO2)

Weathered gray stone, possibly gneiss or granite with attached dark mineral coating

Uncertain; likely quartz–feldspar–biotite rock (granite) or banded gneiss

Sandstone (Quartzose)

Arenite (primarily SiO2)

Sandstone (likely Arkosic or Lithic Sandstone)

Arenite (composed primarily of SiO2 with various lithic fragments)