Crystals
Apatite
Apatite mineral group Ca5(PO4)3(F,Cl,OH) Hexagonal crystal system Mohs 5 Fluorapatite, hydroxylapatite, and chlorapatite Gem, biological, geological, and industrial importance Apatite: Phosphate Crystals, Neon Color, and the Mineral Architecture of Bones...
Apatite
Apatite mineral group Ca5(PO4)3(F,Cl,OH) Hexagonal crystal system Mohs 5 Fluorapatite, hydroxylapatite, and chlorapatite Gem, biological, geological, and industrial importance Apatite: Phosphate Crystals, Neon Color, and the Mineral Architecture of Bones...
Aragonite
Calcium carbonate mineral CaCO3 Orthorhombic crystal system Polymorph of calcite Mohs 3.5–4 Specific gravity approximately 2.93–2.95 Shells, pearls, coral, caves, and marine sediment Aragonite: Calcium Carbonate in Starbursts, Cave Coral,...
Aragonite
Calcium carbonate mineral CaCO3 Orthorhombic crystal system Polymorph of calcite Mohs 3.5–4 Specific gravity approximately 2.93–2.95 Shells, pearls, coral, caves, and marine sediment Aragonite: Calcium Carbonate in Starbursts, Cave Coral,...
Angelite
Blue massive anhydrite CaSO4 Orthorhombic calcium sulfate Mohs approximately 3–3.5 Three prominent cleavages near 90° Dry storage and gentle handling Angelite: Powder-Blue Anhydrite, Right-Angled Cleavage, and the Memory of Evaporated...
Angelite
Blue massive anhydrite CaSO4 Orthorhombic calcium sulfate Mohs approximately 3–3.5 Three prominent cleavages near 90° Dry storage and gentle handling Angelite: Powder-Blue Anhydrite, Right-Angled Cleavage, and the Memory of Evaporated...
Ammonite
Extinct marine cephalopods Subclass Ammonoidea Early Devonian to end Cretaceous Originally aragonitic chambered shells Calcite, pyrite, silica, and internal molds Ammolite from preserved iridescent shell Ammonites: Chambered Cephalopods, Fossil Sutures,...
Ammonite
Extinct marine cephalopods Subclass Ammonoidea Early Devonian to end Cretaceous Originally aragonitic chambered shells Calcite, pyrite, silica, and internal molds Ammolite from preserved iridescent shell Ammonites: Chambered Cephalopods, Fossil Sutures,...
Chrysantemum
Composite ornamental rock Dark sedimentary matrix Calcite or aragonite: CaCO3 Celestine: SrSO4 Radial crystal aggregates Not a fossil flower Component-dependent hardness Chrysanthemum Stone: Mineral Flowers Written Through Dark Rock Chrysanthemum...
Chrysantemum
Composite ornamental rock Dark sedimentary matrix Calcite or aragonite: CaCO3 Celestine: SrSO4 Radial crystal aggregates Not a fossil flower Component-dependent hardness Chrysanthemum Stone: Mineral Flowers Written Through Dark Rock Chrysanthemum...
Amethyst
Purple variety of quartz SiO2 Trigonal crystal system Mohs 7 Iron-related color centers and irradiation Color-zoned points, clusters, geodes, and gems Amethyst: Violet Quartz, Color-Zoned Crystals, and the Quiet Architecture...
Amethyst
Purple variety of quartz SiO2 Trigonal crystal system Mohs 7 Iron-related color centers and irradiation Color-zoned points, clusters, geodes, and gems Amethyst: Violet Quartz, Color-Zoned Crystals, and the Quiet Architecture...