Lesson 01 · Ore Bodies
What even is an ore?
What you’ll getTell apart a rock, a mineral, a metal, and an ore — and understand the words 'grade' and 'gangue'.
Before we talk about types of ore, let's nail down four words that get mixed up all the time. Get these straight and everything else gets easier.
- Mineral — a naturally occurring solid with one specific chemical recipe and an orderly internal structure. Think of it as a natural chemical compound. Salt, quartz, and pyrite are minerals.
- Rock — a mixture of minerals packed together. A rock is like a fruitcake: many ingredients in one lump.
- Metal — the useful element we actually want, like copper, iron, or gold. In the ground, metals are almost always locked inside minerals, chemically joined to other elements.
- Ore — a rock that holds enough valuable mineral that it's worth the money to mine and process. That last part matters: the same rock can be ore in one place and worthless in another, depending on how much metal it holds and what the metal sells for.
Two more words you'll meet constantly:
- Grade — how rich the ore is, usually the percentage of valuable metal in it. High grade means lots of metal per tonne of rock; low grade means only a little.
- Gangue (said "gang") — the worthless rock mixed in with the valuable mineral. The whole job of processing is to throw the gangue away cheaply and keep the metal.
Hold onto this pictureThink of ore as a chocolate-chip cookie. The chips are the valuable mineral. The dough is the gangue. The grade is how many chips are in each cookie. Mining digs up the cookie; processing picks out the chips and throws away the dough.
That cookie will follow us through the whole course. Every "ore family" we meet is just a different kind of chip baked into a different kind of dough — and the trick to getting the chips out depends on what kind they are.