Galena
Galena is lead sulfide, PbS, the primary ore of lead and a significant source of silver, crystallizing in the cubic system with a distinctive metallic luster and remarkably high density for its size. Its perfect cubic cleavage produces sharp-edged cubes and stair-stepped fracture surfaces that make it one of the easiest minerals to identify by touch alone. Galena has been mined since antiquity and remains one of the most commercially important sulfide minerals on Earth.
Galena properties at a glance
| Type | Minerals |
|---|---|
| Chemical formula | PbS |
| Mohs hardness | 2.5 |
| Crystal system | Cubic |
| Luster | Metallic, bright |
| Streak | Lead-gray |
| Cleavage | Perfect cubic {001}, three directions at 90° |
| Fracture | Subconchoidal (rarely seen; mostly cleaves) |
| Specific gravity | 7.4–7.6 |
| Transparency | Opaque |
| Common colors | Lead-gray, Silvery gray |
| Rarity | common |
Geology & background
Galena forms primarily in hydrothermal veins and replacement deposits, where lead- and sulfur-bearing fluids precipitate the mineral in fractures and cavities within limestone, dolomite, and other host rocks, often alongside sphalerite, pyrite, and silver-bearing minerals. The Mississippi Valley type deposits of the American Midwest, especially the historic lead-zinc mining districts of Missouri, Wisconsin, and Illinois, produced enormous quantities of galena and gave the town of Galena, Illinois, its name. Other major deposits occur in the Coeur d'Alene district of Idaho and at Broken Hill, Australia.
Collectors prize galena for its perfect cubic crystals with mirror-flat faces, sometimes reaching several inches across in cavities within vein deposits. Because galena is noticeably heavy for its size, its density alone often tips off experienced collectors before any other test is applied. The mineral's softness means specimens should be handled carefully to avoid chipping the sharp cube edges, and prolonged handling can leave a faint metallic residue on the skin due to its lead content.
How to identify Galena
Galena is easily identified by its bright, silvery, metallic luster, cubic crystal habit, and perfect cleavage in three directions at right angles, producing smaller cubes when broken. Its streak is gray to black, hardness is low at 2.5, and its density is unusually high, noticeably heavier in the hand than most other minerals of similar size. It is rarely confused with anything else once its weight and cubic cleavage are noted, though tarnished surfaces can occasionally be mistaken for other dark sulfides until a fresh cleavage face is exposed.
- Compare the specimen's color, luster, crystal habit, grain size, streak, and locality before confirming.
- Use multiple photos when possible, including a fresh surface and a close view of texture.
Where Galena is found
Reported from multiple localities worldwide; verify locality against specimen provenance when available.
How much is Galena worth?
| Entry-level specimen | $2 |
|---|---|
| Typical collector specimen | $20 |
| Premium specimen | $150+ |
Value depends on size, crystal quality, color, locality, rarity, damage, and provenance.
Common uses
- Collector specimens
- Education
- Field identification
- Industrial or lapidary use when suitable
Interesting facts
- Galena was one of the first minerals used for radio detection, since natural crystals can rectify radio signals in simple cat's whisker crystal radios.
- A single cubic inch of galena weighs nearly twice as much as the same volume of steel, reflecting lead's exceptional density.
- The Missouri lead belt, built almost entirely on galena mining, has produced lead continuously since French colonists began operations in the early 1700s.
Care & safety
Handle as a collector specimen until hardness, cleavage, and fracture are verified.
Avoid inhaling dust. Do not cut, grind, or polish unknown specimens without eye protection and a proper respirator.
.jpg?width=320)
.jpg?width=320)