Pearl Gemstone Chemical Formula                                                   CaCO3 (92% Aragonite) and conchiolin (6%) Color                                                                          White, Cream Hardness                                                                   2.5 – 4.5 Crystal System                                                         Amorphous Refractive Index                                                       1.52 – 1.69 Specific Gravity                                                        2.6 – 2.85 Transparency                                                           opaque Double Refraction                                                   0.156 Luster                                                                        Pearly Cleavage                                                                   None   Mineral Class                                                                     […]