Igneous, Sedimentary, And Metamorphic

Quartz (Raw Chunk)

Silicon Dioxide (SiO2)

Quartz (Milky/Common Quartz)

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Mixed rock and mineral specimen collection

Varied silicate, carbonate, and oxide minerals; individual identification is not possible from this group photograph

Milky Quartz

Silicon Dioxide (SiO2)

Small weathered mineral/rock fragment

Indeterminate; possibly quartz-bearing feldspathic rock or calcite-rich specimen

Green Opal

Hydrated Silica (SiO2·nH2O)

Clear Quartz

Silicon Dioxide (SiO2)

Mixed collection of natural stones

Several unidentified lithologies, likely including basalt, granite, quartzite, sandstone, and weathered metamorphic rocks

Quartz

SiO2 (Silicon Dioxide)

Mixed rock and mineral specimen collection

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

Quartz

Silicon Dioxide (SiO2)

Mixed rock and mineral collection

Multiple specimens; visible pieces may include quartz, calcite, agate/chalcedony, jasper, and dyed or coated materials

Rounded quartz-rich river pebbles

Alluvial gravel; commonly quartzite, chert, and quartz-bearing sandstone fragments

Metallic sulfide mineral fragment, likely galena

Galena (lead sulfide, PbS), tentative identification

Milky Quartz

Silicon Dioxide (SiO2)

Raw selenite (gypsum)

Gypsum, CaSO₄·2H₂O; translucent variety selenite

Carved red coral bead (likely coral or coral-colored resin)

Corallium spp. (precious coral; calcium carbonate, CaCO₃)

Fossil shark tooth

Likely fossilized shark tooth, possibly *Carcharocles* or *Otodus* species

Unidentified Rock Fragment

Unknown

Clear calcite cleavage fragment

Calcite (calcium carbonate, CaCO₃)

Polished malachite

Malachite, Cu₂CO₃(OH)₂

Tumbled quartz-rich pebble

Microcrystalline quartz (SiO₂), possibly milky quartz or chalcedony

Fossil shark tooth

Likely fossilized shark tooth, possibly Carcharhinus or Otodus species

Pearl

Pearl; primarily aragonite (CaCO₃) in nacre

Amethyst

Amethyst (Silicon Dioxide, SiO2)

Quartz (chalcedony variety) or Limestone with Quartz Veins

SiO2 (for Quartz/Chalcedony); CaCO3 (for Limestone)

Pearl-bearing oyster shell

Nacreous shell, primarily aragonite (CaCO₃), with natural pearls (calcium-carbonate nacre)

Desert rose

Gypsum (selenite) rosette, CaSO₄·2H₂O

Yellow-green serpentine (likely)

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

Pearl

Nacre (aragonite, CaCO₃, in an organic conchiolin matrix)

Tumbled amethyst

Amethyst, purple variety of quartz (SiO₂)

Banded calcite (likely cave deposit or vein fragment)

Calcite, CaCO₃

Pearl necklace

Pearl—biogenic calcium carbonate, primarily aragonite (CaCO₃)

Likely anthracite coal fragments

Anthracite; predominantly carbon (C), with minor mineral ash

Probable amber fragment

Amber (fossilized plant resin; chiefly amorphous organic resin, commonly dominated by succinite)

River Stone / Pebble

Clastic Sediment (composed largely of Quartz, Feldspar, and various rock fragments)

Tiger’s eye

Quartz variety, primarily silicon dioxide (SiO₂); fibrous quartz pseudomorph after crocidolite asbestos

Rhodonite

Rhodonite, manganese inosilicate — MnSiO₃; the specimen may include quartz, feldspar, and black manganese-oxide minerals in the matrix

Chalcedony (Banded/Mottled Variety)

Chalcedony (a cryptocrystalline variety of Quartz, SiO2)

Mixed Rock Collection (Pebbles and Stones)

Various geological specimens

Mixed collection of minerals and rocks (Jasper, Carnelian, Granite, and Quartz)

Silicon Dioxide (SiO2) with varying impurities for silicates and igneous aggregates