Anthropogenic (Man Made Material)

Quartzite

Quartzite (SiO2)

Pink Marble

Recrystallized Limestone (Calcium Carbonate, CaCO3)

Fossil Shark Tooth

Carcharocles or Lamniformes (order)

Chert (Field-collected Arrowhead-shaped Fragment)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Fossiliferous Limestone (Coquina)

Biogenic Limestone (Calcium Carbonate, CaCO3)

Native Silver

Silver (Ag)

Chert (specifically Gray/Blue-Gray Chert)

Chert (SiO2)

Blue-dyed Quartz Druzy

Silicon Dioxide (SiO2) with artificial pigment

Quartzite

Quartzite (SiO2-rich metamorphic rock)

Sandstone

Arenite (primary component SiO2)

Sandstone

Arenite (SiO2 based)

Blue Sphalerite (likely dyed or treated Druzy Quartz/Agate)

Zinc Sulfide (ZnS) or Silicon Dioxide (SiO2) with trade-name enhancement

Tumbled yellow quartz (likely citrine or iron-stained quartz)

Quartz, SiO₂; yellow color from trace iron or irradiation/heat-related coloration

Crushed Stone / Gravel

Aggregate (mixed lithology)

Chert (Jasper / Quartz pebble)

Microcrystalline Quartz (SiO2)

Pearl (with Peridot)

Calcium carbonate (CaCO3) + Conchiolin; Peridot: Magnesium iron silicate (Mg, Fe)2SiO4

Chert (Iron-stained)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Quartzite

Quartzite (SiO2)

Carnelian/chalcedony rough

Microcrystalline quartz (SiO₂), iron-oxide-colored chalcedony

Basaltic Tuff / Volcanic Breccia

Pyroclastic Breccia / Lithic Tuff

Polymictic breccia, possibly volcanic breccia

Polymictic clastic breccia; likely a matrix-supported breccia containing lithic fragments, quartz, feldspar, and dark mafic minerals

Tiger’s-eye bead bracelet

Chatoyant quartz, principally quartz (SiO₂) with pseudomorphic fibrous crocidolite/goethite inclusions

Banded iron formation fragment (likely hematite–magnetite ironstone)

Banded iron formation; chiefly hematite (Fe₂O₃), magnetite (Fe₃O₄), and microcrystalline quartz (SiO₂)

Chert (and Jasper/Flint variety)

Cryptocrystalline Quartz (SiO2)

Blue Quartz (Aventurine)

Silicon Dioxide (SiO2) with fibrous inclusions (commonly Dumortierite)

Tektite (Indochinite)

Tektite (High-silica impact glass)

Chert Pebble

Microcrystalline silica (SiO2)

Sandstone

Arenite (SiO2 primarily)

Limestone

Calcium Carbonate (CaCO3)

Limestone

Sedimentary Calcium Carbonate (CaCO3)

Orbicular Granite (specifically Mustard or Yellow Tonalite/Granodiorite)

Orbicular Quartz Diorite / Tonalite

Limestone (Weathered)

Sedimentary Carbonate Rock (CaCO3)

Turquoise

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

Tumbled or rough turquoise-like specimen

Turquoise, hydrated copper aluminum phosphate — CuAl₆(PO₄)₄(OH)₈·4H₂O; identification is uncertain from the image

Chert (Flint)

Microcrystalline Quartz (SiO2)

Diamond

Carbon (C)

Polished black stone egg, probably black obsidian

Obsidian, a natural volcanic glass; composition primarily silica-rich glass (approximately SiO₂), with variable iron and other trace elements

Limestone

Calcium Carbonate (CaCO3)

Chert / Flint

Cryptocrystalline quartz (SiO2)

Granite

Granite

Limestone

Calcium Carbonate (CaCO3)

Garnet Schist

Garnetiferous Mica Schist