Unknown (Likely Sedimentary Or Metamorphic)

Dark gneiss or amphibolite cobble

Banded metamorphic rock, likely quartz–feldspar–biotite gneiss or amphibolite

Desert rose

Gypsum (selenite) rosette, CaSO₄·2H₂O

Weathered sandstone or iron-stained quartzite

Quartz-rich sandstone; possibly weakly metamorphosed quartzite (SiO₂ with iron-oxide coatings)

Small metallic mineral fragment

Indeterminate; possibly galena, hematite, magnetite, or metallic meteorite fragment

Weathered schist or gneiss cobble

Foliated silicate rock, likely mica schist or biotite gneiss

Pyrite cluster (iron pyrite)

Pyrite, FeS₂

Quartz-rich metamorphic fragment (likely mica schist)

Mica schist, probably muscovite–quartz schist

Quartzite with Chert inclusions

Metamorphosed Quartz-rich Rock (SiO2)

Banded calcite (likely marble or calcite-rich limestone)

Calcite, CaCO₃; possibly calcitic marble

Likely graphite-rich metamorphic rock (graphitic schist)

Graphitic schist; chiefly carbon (graphite) with quartz, mica, and possibly sulfides

Granite Gneiss with Garnet

Garnetiferous Gneiss

Weathered quartz-rich pebble, possibly quartzite or chert

Quartz (SiO₂), possibly quartzite; exact identification is uncertain from the image

Likely biotite-bearing metamorphic rock (schist or gneiss)

Mica schist/gneiss; chiefly quartz, feldspar, and biotite mica

Quartz-veined metamorphic rock, likely schist or gneiss

Micaceous quartz-feldspar rock; probable mica schist/gneiss with quartz veins

Coarse-grained metamorphic rock, likely gneiss

Biotite–quartz–feldspar gneiss (tentative; exact identification requires testing)

Pyrite-bearing metamorphic rock (probable pyrite schist or sulfide ore)

Pyrite (FeS₂) in a foliated, quartz–mica-rich host rock; exact identification requires testing

Weathered quartz-rich rock, possibly quartzite or iron-stained quartz

Quartzite (mostly SiO₂), with possible iron-oxide staining and minor feldspar/mica

Light-colored sandstone or quartzite

Quartz-rich sandstone; possibly weakly metamorphosed quartzite

Weathered sandstone or iron-stained quartzite

Quartz-rich sandstone; possibly weakly metamorphosed quartzite (SiO₂-dominant)

Quartz-rich rock, likely milky quartz with iron staining

Quartz (SiO₂), possibly quartzite or quartz vein material

Rounded gray pebble, possibly limestone or quartzite

Uncertain; likely micritic limestone (calcite, CaCO₃) or fine-grained quartzite (quartz, SiO₂)

Gneiss (with Mica and Quartz)

Gneissic Metamorphic Rock

Green Opal

Hydrated Silica (SiO2·nH2O)

Polished orbicular jasper beads

Jasper, microcrystalline quartz (SiO₂) with iron-oxide and other inclusions

Rounded weathered pebble, likely chert or fine-grained quartzite

Microcrystalline quartz (SiO₂), probable chert; quartzite is an alternative

Quartzite river stone

Quartzite (SiO2)

Quartz Vein in Siltstone

Silicon Dioxide (SiO2) within Sedimentary/Metamorphic Matrix

Foliated Metamorphic Rock (likely Gneiss or Schist)

Gneissic Metamorphic Rock

Weathered quartz-rich metamorphic rock, likely gneiss or quartzite

Quartz (SiO₂)-bearing gneiss; exact identification requires a fresh surface and tests

Biotite-rich gneiss (possibly mica schist)

Quartz–feldspar–biotite gneiss; mica-rich metamorphic rock

Amethyst and Hematite Bracelet

Amethyst (SiO2) and Hematite (Fe2O3)

Yellow-green serpentine (likely)

Serpentine-group phyllosilicate, commonly lizardite or antigorite; approximate formula Mg₃Si₂O₅(OH)₄

River Stone (Quartzite/Chert)

Metamorphosed Quartz-rich Sedimentary Rock

Small weathered rock fragment

Indeterminate; possibly granitic or altered feldspathic material

Mixed rock and mineral specimen collection

Multiple species, likely quartz (SiO₂), calcite (CaCO₃), feldspar, chert, and assorted volcanic/sedimentary rocks

Quartz-rich metamorphic rock, likely quartzite

Quartzite; predominantly microcrystalline quartz (SiO₂), possibly with feldspar, mica, and iron-oxide impurities

Pyrite-bearing metamorphic rock (likely greenschist or phyllite)

Quartz–chlorite–mica schist/phyllite with disseminated pyrite (FeS₂)

Dark weathered metamorphic rock, likely schist or phyllite

Undetermined; probably mica-rich quartz–feldspar schist/phyllite

Quartz (Iron-Stained)

Silicon Dioxide (SiO2)

Foliated metamorphic rock, likely biotite schist

Mica schist, chiefly quartz, feldspar, and biotite mica

Quartz

Silicon Dioxide (SiO2)

Banded metamorphic rock, likely gneiss or migmatitic gneiss

Quartz–feldspar–mica gneiss; exact identification requires a fresh surface and mineral tests