Galena
PbS · Cubic · also called lead glance
Galena is lead sulfide, and it behaves exactly the way a lead mineral should: soft, extremely heavy, and bright metallic gray. Its perfect cubic cleavage is unmistakable — few other minerals break into neat right-angled blocks like this.
Properties
- Mohs hardness
- 2.5–2.75
- Streak
- lead gray
- Lustre
- metallic
- Colour
- Bright silvery lead-gray when fresh, dulling to a matte gray with age.
- Cleavage
- Perfect cubic cleavage in three directions at right angles. Broken pieces fall apart into little stepped cubes — this is the giveaway.
- Fracture
- Subconchoidal, rarely seen because cleavage dominates
- Specific gravity
- 7.4–7.6 (water = 1)
- Magnetism
- Not magnetic
- Acid test
- No reaction
- UV
- Not fluorescent
Tests that confirm galena
- Startlingly heavy for its size — the heaviest common mineral most collectors will handle.
- Tap a piece with a hammer and it splits into perfect cubes.
- Soft enough to scratch with a copper coin.
What galena gets confused with
Each of these is settled by one test. Run that test first.
Graphite is far lighter, feels greasy, and marks paper. Galena is dense and does not smudge.
Stibnite forms slender bladed crystals with one-direction cleavage, not cubes.
Where it is found
Hydrothermal veins and limestone-hosted deposits. The Tri-State district of the American Midwest and the English Pennines are classic sources.
Is it worth anything?
Common material is inexpensive. Wash your hands after handling it — galena is a lead mineral, and it should not be tumbled, licked, or given to children.