Mineral (Synthetic)

Ironstone Concretion

Siderite or Hematite Concretion

Red Sandstone

Arenite (primarily Quartz, SiO2, with Iron Oxide cementing agent)

Turquoise

CuAl6(PO4)4(OH)8·4H2O

Fossilized Bone Fragment

Permineralized Vertebrate Bone (Hydrox yapatite replaced by Silica or Calcite)

Ironstone (with Limonite/Goethite)

Ferruginous Sedimentary Rock (contains Limonite FeO(OH)·nH2O and Hematite Fe2O3)

Dendritic Agate

Silicon Dioxide (SiO2) with inclusions of manganese or iron oxides

Azurite and Malachite on Matrix

Azurite: Cu3(CO3)2(OH)2; Malachite: Cu2CO3(OH)2

Desert Rose (Sand Barite/Gypsum Rose)

Barium Sulfate (BaSO4) or Hydrated Calcium Sulfate (CaSO4·2H2O)

Turquoise

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

Turquoise

CuAl6(PO4)4(OH)8·4H2O

Brown Sandstone

Arenite (primarily Quartz and Feldspar, with Iron Oxide cement)

Botryoidal Goethite

Goethite (α-Fe3+O(OH))

Sandstone (Ferruginous)

Arenite with Iron Oxide cement (SiO2 + Fe2O3)

Quartz Geode

Crystalline Silicon Dioxide (SiO2) within a nodule

Quartz Pebble (with Mica or Iron staining)

Silicon Dioxide (SiO2)

Geode (Unopened)

Silica-rich Concretion (primarily SiO2)

Sandstone (Quartzose Sandstone)

Sandstone (SiO2 with various trace minerals)

Desert Rose (Gypsum/Baryte)

Hydrated Calcium Sulfate (CaSO4·2H2O)

Quartz Geode with Goethite/Hematite

Silicon Dioxide (SiO2) with Iron Oxides

Fire Opal in Host Rock

Amorphous Hydrous Silica (SiO2·nH2O)

Biotite Mica

Biotite (K(Mg,Fe)3AlSi3O10(OH,F)2)

Sunstone

Oligoclase (Plagioclase Feldspar), (Na,Ca)(Si,Al)4O8

Amethyst

Silicon dioxide (SiO2) with iron impurities

Prehnite

Prehnite (Ca2Al(AlSi3O10)(OH)2)

Malachite with Chrysocolla

Copper carbonate hydroxide (Cu2CO3(OH)2) and Hydrated copper silicate (Cu,Al)2H2Si2O5(OH)4·nH2O

Goethite pseudomorph after Pyrite

Goethite (FeO(OH)) pseudomorph after Pyrite (FeS2)

Smoky Quartz (Herkimer-style)

Silicon Dioxide (SiO2)

Quartz

Silicon Dioxide (SiO2)

Prehnite

Prehnite (Ca2Al(AlSi3O10)(OH)2)

Green Fluorite

Calcium Fluoride (CaF2)

Chakra Tumbled Stone Set

Various (including Amethyst [SiO2], Sodalite [Na8(Al6Si6O24)Cl2], Green Aventurine [SiO2], Red Jasper [SiO2], etc.)

Iron-stained Quartz (Gossan/Limonite-coated Quartz)

Silicon Dioxide (SiO2) with Hydrated Iron Oxides (FeO(OH)·nH2O)

Tiger's Eye

Tiger's eye (Pseudomorph of Quartz after Crocidolite), SiO2

Sandstone (likely River-tumbled Picture Sandstone)

Arenite (predominantly SiO2 with iron oxide impurities)

Pyrite

Iron Sulfide (FeS2)

Hematite (Iron Ore)

Hematite (Fe2O3)

Green Calcite

Calcium Carbonate (CaCO3)

Quartz

Silicon Dioxide (SiO2)

Biotite (Mica)

Biotite group (K(Mg,Fe)3AlSi3O10(F,OH)2)

Basalt-Amugydule (Amygdaloidal Basalt)

Aphanitic Mafic Igneous Rock with Vesicle Infillings

Basalt with Quartz Vein

Basalt (SiO2 vein inclusion)

Sandstone with Iron Staining

Arenite with Limonite/Hematite inclusions (SiO2 + Fe2O3/FeO(OH))