Synthetic Polymer (Polylactic Acid)

Moonstone (bead form)

Potassium Aluminum Silicate (KAlSi3O8) - a variety of Orthoclase Feldspar

Dolomite or Limestone (Carbonate Rock)

CaMg(CO3)2 (Dolomite) or CaCO3 (Limestone / Calcite)

Limestone

Calcium Carbonate (CaCO3)

Quartzite

Metamorphosed Quartz Sandstone (SiO2)

Marble

Metamorphosed Limestone (mainly CaCO3)

Green Quartzite (River Stone)

Metamorphic Quartz (SiO2) with inclusions (typically Fuchsite or Chlorite)

Quartzite

Quartzite (SiO2)

Limestone

Calcium Carbonate (CaCO3)

Sandstone or Limestone

Arenite or Calcareous Sedimentary Rock

Sandstone (likely Graywacke or Arkose variant)

Clastic Sedimentary Rock (SiO2 based)

Granite

Granite (Felsic Plutonic Rock)

Limestone (Buff/Tan)

Calcium Carbonate (CaCO3)

Calcite

Calcium Carbonate (CaCO3)

Azurite in Matrix

Azurite (Cu3(CO3)2(OH)2)

Quartzite

Quartzite (SiO2)

Quartzite Pebble

Metamorphosed Quartz Sandstone (SiO2)

Quartzite

Meta-sandstone (mostly SiO2)

Seashell Fragment (Aragonite/Calcite)

Calcium Carbonate (CaCO3) - Shell fragment

Granite Cobble

Granite (Phaneritic Igneous Rock)

Orange Calcite

Calcium Carbonate (CaCO3)

Rhodonite

Rhodonite (Mn,Fe,Mg,Ca)SiO3

Turquoise

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

Limestone

Calcium Carbonate (CaCO3)

Quartzite (with Iron Staining)

Metamorphosed Quartz Sandstone (SiO2)

Quartzite

Quartzite (SiO2)

Limestone (River Pebble)

Sedimentary Calcium Carbonate (CaCO3)

Fossiliferous Limestone

Calcium Carbonate - CaCO3

Diamond in Gold Setting

Diamond (C - pure carbon)

Banded Calcite (often sold as Orange Onyx or Mexican Onyx)

Calcium Carbonate (CaCO3)

Quartzite (River Stone)

Silicon Dioxide (SiO2)

Sandstone (Ferruginous/Red Sandstone)

Clastic sedimentary rock (primarily SiO2 with Fe2O3)

Banded Calcite (often sold as Caribbean Calcite or Pink Calcite)

Calcium Carbonate (CaCO3)

Quartzite Pebbles

Meta-quartzite (SiO2)

Red Sandstone

Arenite (primarily Quartz, SiO2, with Iron Oxide/Hematite)

Limestone

Calcium Carbonate (CaCO3)

Chalk

Carbonate rock (mainly CaCO3)

Limestone

Calcareous sedimentary rock (CaCO3)

Limestone (Fossiliferous)

Calcium Carbonate (CaCO3)

Chert (varieties include Jasper or Flint)

Chert (Microcrystalline Silica, formula: SiO2)

Limestone

Calcium Carbonate (CaCO3)

Quartzite

Quartzite (SiO2)

Chert (variously known as Flint or River Pebble)

Microcrystalline or Cryptocrystalline Quartz (SiO2)