Lead is one of the first metals to have been used by humans, dating back to about 6500 BC. Today, the United States is the world's leading producer of lead, and galena (the primary ore of lead and silver) has been mined here in huge quantities since the 19th century, when the need for extensive plumbing arose from the influx of people to cities.
Galena has been such an important mineral for miners that they have named other minerals based on their resemblance. A similar metallic black mineral that is the primary ore of zinc was dubbed sphalerite by miners, which is Greek for treacherous rock, and is also called blende, which is German for blind or deceiving - because it was much less valuable than galena!
Unfortunately, it was later determined that lead, while easy to work and inexpensive, came with a hidden high price -- it was poisonous. Luckily (for rockhounds), in its sulfide mineral form (galena), lead is not generally harmful to handle. (However, do not ingest galena; we recommend washing your hands after handling, just to be on the safe side.)
We still use lead for anti-knock gasoline additives, car batteries, protection from radioactivity, solder, paints, varnishes, and glazes -- but no longer for plumbing or house paint. Galena is also a popular mineral for collectors both young and old, because it has some very interesting properties:
- a striking, silver-grey color, sometimes with a bluish tint
- a bright metallic luster on broken faces that dulls with weathering (due to the oxidation of the lead within)
- a crystal habit that is most often cubical, octahedral, or a combination thereof
- cleavage in four directions, forming perfect cubes
- hardness of 2.5 Mohs (about as hard as your fingernail)
- a specific gravity of 7.4 - 7.6 -- one cubic foot of galena weighs about 700 pounds!
Galena is, by far, the heaviest mineral that most of us will ever have the opportunity to hold a large chunk of. Only gold, iridium, platinum, and tungsten are heavier.
Galena: PbS, Lead Sulfide
Mohs scale hardness: 2.5 - 2.75
Class: Sulfide mineral
Color: Lead gray and silvery
Crystal system: Cubic Hexoctahedral cF8, space group Fm3m, No. 225
Crystal habit: Cubes and octahedra, tabular and sometimes skeletal crystals
Specific gravity: 7.2–7.6
Cleavage: Cubic perfect on , parting on 
Streak: Lead gray