This is the mineral Galena. It has a metallic luster and a dark grey to black streak. Galena contains only 2 elements, Lead and Sulfur, and has the chemical formula PbS. It thus belongs to the Sulfide chemical family. Sulfides are minerals consisting of Sulfur and one or more metals. It ranks 2.5 on Mohs hardness scale, which is relatively soft and about as hard as your fingernail. Thus, Galena could scratch the minerals Gypsum and Talc, but not Fluorite or Calcite. Galena exhibits perfect cubic cleavage, which is remarkably visible after striking a sample with a rock hammer. The spalled fragments are small cubes of varying sizes. Note that the mineral grows as a cube as its two elemental components, Lead and Sulfur, chemically combine. Its specific gravity averages about 7.5, which makes it feel very heavy in your hand. Galena is the most significant source of Lead and has been smelted to acquire this malleable element for over 8,000 years. The Lead from Galena was used in ancient Rome to construct lead pipes for aqueducts, mint lead coins, and cast projectiles for use in war. It was also used to sweeten food and control fermentation during winemaking. Today, the Lead from Galena is used in lead-acid batteries, ammunition, pigments, solder, and roofing materials. Since Lead is toxic, many countries have adopted strict environmental regulations concerning its use. Thus, you may have heard that lead-based paints and leaded gasoline are no longer available. You may also hear that many public water systems are assessing the extent of their lead-based service lines in preparation for their replacement. Even with these concerns, however, you do not need to worry about acquiring lead toxicity when handling a sample of Galena. It’s safe in its massive form, but not if inhaled as fine dust.