Railsback's Some Fundamentals of Mineralogy and Geochemistry Density of minerals IV: Simple anions He N3- O2- F- Ne This plot shows the density of minerals with simple P3- S2- Cl- Ar anions (e.g.,Cl-, O2-, or P3-) as opposed to those with 3- 2- - Kr complex anions (e.g., the CO 2- of CaCO ). At least three As Se Br 3 3 3- 2- - things emerge. First, more dense anions lead to more Sb Te I Xe dense minerals, as the upward trend of all the linking lines minerals with 3- anions shows. For example, tellurides are more dense than triangles (nitrides, phosphides, etc.) selenides of the same cation, which are more dense than squares & minerals with 2- anions sulfides of the same cation. Secondly, minerals with 3- diamonds (oxides, sulfides, selenides, etc.) anions are more dense than corresponding minerals with 2- circles minerals with 1- anions (halides) anions, which are more dense than blue Cu-bearing minerals minerals with 1- Massicot PbO red Fe-bearing minerals anions (the black minerals of other cations Lithargite PbO halide minerals). filled symbols minerals Finally, minerals 9 open symbols non-mineral synthetics with anions from the top row of the Cu3Sb periodic table Monteponite CdO Altaite PbTe Frohbergite (oxides and, to a Clausthalite PbSe FeTe2 8 FeAs Volynskite lesser extent, ) 3 AgBiTe fluorides) are Bohdanowiczite 2 AgBiSe unusally dense Galena PbS Domeykite 2 Melonite Cu As compared to 3 Ferroselite NiTe2 FeSe minerals with 2 Vulcanite CuTe 7 Matildite AgBiS2 anions of the Trogtalite CoSe2 Cu3P Bunsenite NiO same charge. Kullerudite NiSe2 For example, Density (gm/cm Tenorite CuO oxides are much Cuprite more dense than Klockmannite CuSe 6 Cu2O sulfides of the FeP Chalcocoite Marshite CuI same cation, and Cu S Wustit¨ e FeO Cu N 2 commonly more 3 Manganosite MnO Cadmoselite CdSe Millerite NiS dense than Pyrite FeS Magnetite Fe3O4 selenides and 2 5 Cattierite CoS2 even tellurides of Troilite FeS Pyrolusite MnO2 CuBr Hawleyite CdS the same cation. Covellite CuS This difference is Vaesite NiS2 probably due to LiI Greigite Fe S differences in 3 4 4 Alabandite MnS Nantokite CuCl bonding and illustrates why FeF LiBr NaI sulfides, 3 Hauerite MnS2 selenides, and NaBr tellurides are 3 Villiaumite NaF KI commonly Molysite FeCl3 categorized Griceite LiF KBr Carrobite KF together but Halite NaCl never lumped with the oxides. 2 LiCl Sylvite KCl 0.5 1.0 1.5 2.0 2.5 3.0 Ionic density of anion (atomic weight in amu ÷ volume of ion in Å3) LBR 4DensityIdes123plot06 1/2007 rev 2/2008.