Where do mineral ores come from?

The core of the planet of Scarterra is the Elemental Plane . Periodically the elemental plane releases new elements into the material plane.
It's normally not that big of a deal if new air or water is created, but it's very noticeable when minerals force their way into Scarterra that issues arise. Periodically this creates earthquakes or volcanic activity. It also impacts who has access to the wealth of the earth and who does not.
Regulating this is primarily Hallisan's Dominion but the rest of the Nine sometimes choose to poach on Hallisan's domain and interfere with what minerals go where.
That means it's possible to have a self-replenishing mine (nicknamed "a hot mine").  Hallisan preaches about fairness and justice but he is not above playing favorites with mortals (hence why the rest of the Nine often feel morally justified interfering with Hallisan's domain).
A "cold mine" is also called a "normal mine". Cold mines are actually replenished the same way hot mines it's just that the replenishment events are so rare that most mortals have no realistic chance of witnesses one, especially in a predictable manner.
There are also so called "luke warm" mines that fall in between the extremes cold mines and hot mines, but it is difficult to quantity where cold ends and luke warm begins. Sometimes the term "luke warm" is motivated by wishful thinking, with the mine owner hoping to get a sudden influx of new riches at any given point but these events do have the short-term problem of nasty earthquakes.
Most self replenishing mines are held by dwarves.  It's a debate whether this is because Hallisan is showing favoritism to dwarves or simply that dwarves are better at finding these sites.

Type

Metaphysical, Elemental