Gadolinite is a mineral of a nearly black color and vitreous luster, and consisting principally of the silicates of cerium, lanthanum, neodymium, yttrium, beryllium, and iron with formula: (Ce,La,Nd,Y)₂FeBe₂Si₂O₁₀. Called gadolinite-(Ce) or gadolinite-(Y) depending on the prominence of the variable element composition. This article is about minerals in the geologic sense; for nutrient minerals see dietary mineral; for the band see Mineral (band). ... For the file system called Lustre, see Lustre (file system) Lustre (American English: luster) is a description of the way light interacts with the surface of a crystal, rock or mineral. ... The silicate minerals make up the the largest and most important class of rock-forming minerals. ... General Name, Symbol, Number cerium, Ce, 58 Chemical series lanthanides Group, Period, Block ?, 6, f Appearance silvery white Atomic mass 140. ... General Name, Symbol, Number lanthanum, La, 57 Chemical series lanthanides Group, Period, Block 3, 6, f Appearance silvery white Atomic mass 138. ... General Name, Symbol, Number Neodymium, Nd, 60 Chemical series Lanthanides Group, Period, Block _ , 6, f Density, Hardness 6800 kg/m3, no data Appearance silvery white, yellowish tinge Atomic properties Atomic weight 144. ... General Name, Symbol, Number yttrium, Y, 39 Chemical series transition metals Group, Period, Block 3, 5, d Appearance silvery white Atomic mass 88. ... General Name, Symbol, Number beryllium, Be, 4 Chemical series alkaline earth metals Group, Period, Block 2, 2, s Appearance white-gray metallic Atomic mass 9. ... General Name, Symbol, Number iron, Fe, 26 Chemical series transition metals Group, Period, Block 8, 4, d Appearance lustrous metallic with a grayish tinge Atomic mass 55. ...