Galena vs Molybdenite
Galena and Molybdenite are commonly confused, and 5 measured properties separate them — cleavage most clearly.
Galena vs Molybdenite
Galena
PbS
Lead sulfide — heavy, metallic, splitting into perfect cubes, and the ore that has supplied nearly all the world's lead since antiquity.
Molybdenite
MoS2
Molybdenum disulfide — the ore of molybdenum, a dry lubricant that works where oil burns, and so soft it marks paper like graphite.
| Property | Galena | Molybdenite |
|---|---|---|
| Cleavage Categorical values can be listed side by side but not ordered or subtracted. | perfect in three directions at right angles, giving cubes | perfect in one direction |
| Crystal system Categorical values can be listed side by side but not ordered or subtracted. | cubic | hexagonal |
| Density | 7.2–7.6 g/cm³ higher | 4.6–5.1 g/cm³ |
| Lustre Categorical values can be listed side by side but not ordered or subtracted. | metallic | metallic |
| Mohs hardness Mohs hardness is an ordinal scale: values can be ranked, but differences and ratios between them are not meaningful. | 2.5–2.75 higher | 1–1.5 |
| Streak Categorical values can be listed side by side but not ordered or subtracted. | lead grey | bluish grey |
Why these get confused
both soft, heavy and metallic grey; molybdenite is named from the Greek for lead because it, graphite and galena were long taken for one substance
The confusion is a real and documented one, not a resemblance we have invented.