Graphite vs Molybdenite
Graphite and Molybdenite are commonly confused, and 4 measured properties separate them — density most clearly.
Graphite vs Molybdenite
Graphite
C
Carbon in stacked sheets — soft, slippery, electrically conductive, and chemically identical to diamond.
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 | Graphite | Molybdenite |
|---|---|---|
| Cleavage Only one of the two has a figure we can stand behind, so there is nothing to compare. | Not known | perfect in one direction |
| Crystal system Categorical values can be listed side by side but not ordered or subtracted. | hexagonal | hexagonal |
| Density | 2.09–2.23 g/cm³ | 4.6–5.1 g/cm³ higher |
| Lustre Categorical values can be listed side by side but not ordered or subtracted. | metallic to dull | metallic |
| Mohs hardness Mohs hardness is an ordinal scale: values can be ranked, but differences and ratios between them are not meaningful. | 1–2 higher | 1–1.5 |
| Streak Categorical values can be listed side by side but not ordered or subtracted. | black | bluish grey |
Choosing between them
Molybdenite is recorded as a substitute for Graphite — better at temperature.
What it gives up: More expensive, and it oxidises above about 400 °C in air where graphite does not.
In this application, on the evidence cited above.
Why these get confused
the reason molybdenite is named after lead: it, graphite and galena were long taken for one substance
The confusion is a real and documented one, not a resemblance we have invented.