Synthetic Polymer (Polylactic Acid)

Honey-brown calcite crystal cluster

Calcite (CaCO₃), likely dogtooth or scalenohedral calcite

Orange Calcite

Calcium Carbonate (CaCO3)

Calcite

Calcium Carbonate (CaCO3)

Calcite (likely honey/orange calcite)

Calcite — calcium carbonate, CaCO₃

Mixed rock and mineral specimen collection

Mostly undetermined from the photograph; apparent quartz-rich rocks, sandstone, granite/gneiss, and possibly iron-oxide-bearing specimens

Blue Calcite

Calcium Carbonate (CaCO3)

Ferruginous Quartz (Iron-stained Quartz)

Silicon Dioxide (SiO2) with Iron Oxide (Fe2O3) inclusions

Calcite

Calcium Carbonate (CaCO3)

Travertine (often colloquially called Tufa)

Chemical Sedimentary Calcium Carbonate (CaCO3)

Agatized fossil clam/bivalve specimens

Fossil bivalve shells, partly replaced or infilled by chalcedony and quartz (SiO₂)

Fossil brachiopod shell

Brachiopoda indeterminate; possibly a strophomenid or spiriferid

Rounded gray river pebble, likely fine-grained sandstone or siltstone

Indeterminate clastic sedimentary rock; possibly quartz-rich sandstone or siltstone

Silicified fossil-bearing limestone (likely chert/agate replacement)

Microcrystalline quartz (SiO₂) replacing carbonate rock; possible fossiliferous limestone

Fossil shell fragment, likely brachiopod or bivalve

Indeterminate fossilized carbonate shell; possibly Spiriferida (brachiopod)

Polished malachite

Malachite (Cu₂CO₃(OH)₂), a hydrated copper carbonate hydroxide

Limestone

Calcium Carbonate (CaCO3)

Polished marble (likely calcitic marble)

Calcite-rich marble; primarily calcium carbonate, CaCO₃

Moonstone

Adularia or Orthoclase (KAlSi3O8) or Albite (NaAlSi3O8), specifically with lamellar exsolution of albite and orthoclase.

Crystal Quartz Beads (likely Clear Quartz)

Quartz (SiO₂)

Aquamarine

Aquamarine (Beryl variety); Be3Al2Si6O18

Limestone

Calcium Carbonate (CaCO3)

Limestone Pebble

Sedimentary Calcium Carbonate (CaCO3)

Fossil oyster shell fragment

Fossilized oyster (Ostreidae), composed mainly of calcite (CaCO₃)

Mixed mineral and rock collection

Predominantly quartz varieties, including amethyst, plus likely calcite, feldspar, mica, and miscellaneous polished stones

Limestone

Calcium Carbonate (CaCO3)

Rounded yellow-brown pebble

Likely iron-stained sandstone or quartz-rich river cobble

Calcite with iron staining

Calcium Carbonate (CaCO3)

Green Calcite

Calcium Carbonate (CaCO3)

Marble (White)

Recrystallized Calcite (CaCO3) or Dolomite (CaMg(CO3)2)

Jade (likely Nephrite or Jadeite)

Nephrite (a variety of actinolite, Ca2(Mg,Fe)5Si8O22(OH)2) or Jadeite (NaAlSi2O6)

Orange Calcite

Calcium Carbonate (CaCO3)

Limestone

Limestone (CaCO3)

Orange calcite (honey calcite)

Calcite, calcium carbonate (CaCO₃)

Fossil shell fragment

Indeterminate molluscan bioclast, likely aragonite or calcite

Rounded weathered stone, likely sandstone or chert

Indeterminate; probable quartz-rich clastic rock (sandstone) or microcrystalline silica (chert)

Weathered sandstone pebble

Quartz-rich sandstone, commonly arkose or lithic sandstone

Limestone with Fossil Fish Fragment

Calcite (CaCO3) containing a fossil teleost

Fossiliferous Limestone (Coquina / Shell Bed)

Biogenic Limestone (Calcium Carbonate, CaCO3)

Orange Calcite

Calcite (CaCO3)

Weathered sandstone or granitic rock fragment

Likely quartz-rich sandstone; exact identification requires testing

Blue opal heart cabochon

Common opal, hydrated amorphous silica (SiO₂·nH₂O), likely blue-dyed or synthetic opalite

Faceted yellow-brown gemstone earring

Likely citrine (quartz, SiO₂), though treated quartz or synthetic glass cannot be confirmed from the image