What you will learn in Minerals and the Rock Cycle

1. 1. What counts as a mineral

   Five conditions, all of which have to hold. Ice in a glacier is a mineral, the water it melts to is not, and granite is not one either — which is the difference between a rock and a mineral.

2. 2. One tetrahedron, six families

   Ninety-two percent of the crust is one shape linked six ways. Count the shared corners and you have the formula, the cleavage and the weathering resistance — all three, from one integer.

3. 3. Identifying a mineral

   Run the tests a geologist runs, and do not start with the colour. Then notice that the hardness number you measured is a ranking, and find out what that costs you at the top of the scale.

4. 4. Igneous rock from a melt

   Two numbers name the rock: how much silica the melt held, and how fast it cooled. Granite and rhyolite are the same melt, and most igneous rock never reached the surface at all.

5. 5. Sediment to rock

   The easiest grain on Earth to move is fine sand, and clay a thousand times smaller is five times harder. That one curve explains muddy rivers, clear streams and why a deposit remembers the flow that made it.

6. 6. The cycle as a network

   Get a sedimentary rock back to being a sedimentary rock without melting it. It can be done, the ring diagram cannot say so, and doing it is the point of the chapter.