I've received the advice that you should always make your charts so that you numbers are proportional to a length, since people aren't good at comparing areas (or volumes).

So the numbers here probably ought to be proportional to diameters

Area of circle

Pronounced "mall-ib(like rib)-den-umm"

Used in steel production since it likes to form carbide when it gets all melty with iron and carbon.

It's one of those elements that you don't really hear about unless you have a specific type of job or hobby set.

I know of it because I make knives and swords, and it's in some steel alloys I use. Some might know of it because it's used in high pressure hydraulic tubes.

But unless you deal with metallurgy, you have no real reason to know much about it.

Really? Are you serious? It’s used for all sorts of things. None of which I can think of right now.

It has its uses, but it’s not exactly something you run into while knowing IMO. I’ve heard of molybdenum disulfide, a type of dry lubricant.

Agree where is coal, but it is hard to track since most of these have a set value and quantity at that time and is usually sold and usually tracked at which amounts, where coal is a different beast, you have different types of coal, like peat, lignite, bituminous and anthracite, then there is even in the same type different grades and quantity, like bituminous coal you will look at the water content, the ash content, amount of macerials.... All of these affect their price. Then some coal is mined and consumed at source, usually powerplants are build right by coalfields, to minimise transportation costs, and the mine might be owned by the powerplant, or with a private contract where the price and quantity would not be disclosed to the public.

But if you look at USA, China, India and Indonesia, I think, so my very biased outlook, their combined coal mining, not only in $ but also in Tonnes, will make oil look like a small footnote.

Actually, our solar power plants are way more efficient than photosynthesis. We just need a lot more power than nature