I know more about the history of oil and therefore coal history in comparison to oil history, but I think you're basically comparing coal to oil here, so that may be appropriate. Coal was the major source of industrialized power in the nineteenth century in much the same way that oil became the major source of industrialized power in the twentieth (though, of course, coal didn't disappear - it's still an important source of power today). However, coal and oil functioned in quite different geopolitical contexts.

The reasons that oil is prone to price fluctuation can get kind of complex, but to some degree they boil down to the differentiation between oil producing nations and oil consuming nations in a global system of (relatively) free-trade capitalism. That is, some nation-states consume far more oil than others, so they seek oil in other places. In a post-colonial context, that means that these nation-states need to buy oil from other nations, so oil production can be very profitable for smaller, less industrialized nations. (Or more typically a handful of people within them.) However, the market forces at work mean that oil embargoes or recessions in one part of the world can have a drastic effect on prices in other parts of the world.

This wasn't the case for coal production. The UK was the first nation to industrialize, and it remained the world's largest coal producer for most of the nineteenth century, until the US overtook it pretty dramatically in the 1890s. (US coal production was nearly double the UK's by 1910.) Other European states - and the US, of course - also produced coal. In other words, the major industrial powers were much more able to address their domestic coal demands with local production. And when nations outside of Europe (and the US) became industrialized and/or began mining coal (and the two were mutually reinforcing - steam-powered railways both rely on coal and enabled its transportation), they usually did so in the context of imperialism. (Primarily) British or French governments or companies would begin the use of coal specifically with British or French consumption in mind. So, some people did get very wealthy from coal, but those people were the colonial European powers, who tended to get all of the wealth, from coal or other sources, at the height of European imperialism in the nineteenth century.

This is certainly not to say that coal had no price fluctuations - it did. But the system that relied upon coal was more stable and less prone to fluctuation in its dominant period than oil was in the twentieth century, especially its second half. This is mostly due to domestic coal production in coal consuming nations and the systemically exploitative nature of coal production in the colonial context. (Though oil extraction was just as systemically exploitative until decolonization, and there are still certainly objections to me made about the distribution of oil wealth today - I don't want to ignore that.)

I hope this answers your question! My main source here is Global Energy Shifts by Bruce Podobnik. Podobnik uses world systems theory, which is objectionable in some ways - breaking the world into hegemonic "center" and "periphery" tends to diminish the actual importance of what was going on outside of Europe and the US - but I think it's quite helpful in understanding the dynamics of coal in the context of colonialism.