In this task, you are given a paragraph, and your task is to construct a question from the given passage. Construct question in such a way that (i) it is well explained in the paragraph, (ii) the words may/may not be present in the paragraph, (iii) it should start with what/how/describe. Avoid creating a question that (i) is just relevant to one or two sentences, and (ii) not relevant to passage. 

Magma cools inside the crust. Magma crystalizes. Lava cools on the surface. Lava crystalizes. Minerals dissolved in water crystlize. 
How do minerals form?