When Neanderthal man wanted fire
His methods will surely inspire,
For he used, if you please,
Some oxide (manganese),
And he then cooked his meat on the pyre.
some research relating to the discovery of lumps of manganese oxide associated with Neanderthal sites. It had been thought that they used it as a black pigment - but in some cases the lumps were found more thane 250 km from where it could be found naturally. But if all they wanted was a black pigment they could have used the far more easy to obtain charcoal.
However if you grind up manganese and sprinkle it over wood it is far easier to get a fire going, and the wood ignites at a lower temperature.