Pyrite Galena and Calcite
Pyrite or iron pyrite is commonly refered to a fool's Gold because its metallic luster and pale brass-yellow hue give it a superficial resemblance to gold. In the old mining days pyrite was sometimes mistaken for gold. Pyrite is the most common of sulfide minerals with the chemical formula Fes2. Pyrite crystals occur in many shapes and habits, including cubes of all sizes, penetration twin cubes, pyritohedral clusters and a small druzy crystals that can exhibit a beautiful glistening effect.
Galena is a lead based mineral that is in fact the primary ore of lead, and has been used for its lead content for thousands of years. Galena typically displays a gray metallic luster and forms cubes or octahedral crystals. The chemical composition of galena is PbS.
Calcite, CaCO3, is a carbonate mineral and most stable polymorph of calcium carbonate. The other polymorphs are the minerals aragonite and vaterite. Calcite crystals are trigonal-rhombehodral, though actual calcite rhombohedral are rare as natural crystals.