Lesson 09 · Ore Bodies
Evaporites — the salts left by drying water
What you’ll getUnderstand salts left behind when water evaporates, what they're used for, and the gentle ways we mine them.
Back to a family defined by how it formed — and it's one you already know from your kitchen.
The definition: when a sea or lake dries up, the salts dissolved in it are left behind as thick beds of crystals. Those are evaporites. Inside this group are two sub-types worth naming simply:
- Halides — a metal joined to a halogen like chlorine. Examples: halite (ordinary rock salt, NaCl) and sylvite (the potassium one, KCl).
- Sulfates — built on a sulfur-and-oxygen group. The big example is gypsum.
What they give us
- Potash (from sylvite) — the potassium in fertiliser. It's a massive industry; Saskatchewan is a world leader.
- Halite — table and road salt, and a feedstock for the chemical industry.
- Gypsum — the core of drywall and plaster for construction.
- Lithium brine — some salt flats hold lithium-rich water. Evaporate it in ponds and you get lithium. This is the second route to lithium, alongside the spodumene rock from last lesson.
How we mine them
Two gentle methods, no furnace required: let the sun evaporate brine in ponds, or use solution mining — pump water down to dissolve a buried salt bed, then pump the salty water back up to dry out and crystallise.
Memory hookEvaporites = salts from dried-up water. Dissolve and evaporate — no smelting.