Galena
Galena is lead sulfide, PbS, a heavy, silver-grey mineral that forms perfect cubes. It is the main ore of lead and often contains silver.
Galena is lead sulfide, PbS, a heavy, silver-grey mineral that forms perfect cubes. It is the main ore of lead and often contains silver.
🪨 Geology Guide Specimen: Open Galena in the CRV Science Rock & Mineral ID Guide to log the specimen, compare it with the other 8 mineral classes of Dana / Strunz Classes, and test your eye in LithoClade.
Cubic Cleavage: How Do You Recognize Galena?
Galena breaks along three perfect cleavage planes at right angles, so a crushed piece splits into smaller and smaller cubes and steps. It is soft, with a hardness of 2.5, bright and metallic when fresh, and extremely dense, about 7.5 grams per cubic centimeter.
Ore Deposits: Where Is It Found?
Galena forms in hydrothermal veins and in carbonate-hosted deposits of the Mississippi Valley type, often with sphalerite and in dolostone or limestone. Many galenas carry traces of silver, and for centuries lead mines were also silver mines.
Uses: From Eye Paint to Radio
Ground galena was used as an eye cosmetic in ancient Egypt. Lead from galena has been used in pipes, glazes, paints, bullets and batteries. Early crystal radios used a galena crystal with a thin wire, the cat's whisker, as a detector. Lead is toxic, so most of these uses have been restricted; see lead.
Galena at a Glance
| Property | Value |
|---|---|
| Type / variety | PbS • Isometric Lead Sulfide |
| Composition | PbS (86.6 wt% Lead; often argentiferous with trace Ag⁺) |
| Geology Guide group | Minerals (8 Major Chemical Groups) |
| Mineral Group | Sulfides |
| Mohs hardness | Mohs 2.5 |
| Texture / habit | Silver-grey cubes and cubo-octahedra |
| Density | 7.40–7.60 g/cm³ (extremely heavy) |
| Lustre and cleavage | Bright metallic lead-grey lustre; PERFECT 3-directional cubic (90°) cleavage; lead-grey streak |
| Geological setting | Mississippi Valley-type carbonate-hosted ore bodies and hydrothermal veins |
| Diagnostic feature (Geology Guide) | Extremely heavy (density 7.5 g/cm³), bright silver-grey metallic cube (Mohs 2.5) that shatters into smaller and smaller 90-degree staircase cubes along three perfect cubic cleavage planes. |
| Formula | PbS |
| Density | About 7.5 g/cm³ |