From the geology course I took in 1975: Minerals are naturally occurring crystals of compound. Snow is a mineral, but volcanic glass is not. Rocks are amalgams of minerals and non-minerals.
In corpus linguistics, a collocation is a sequence of words or terms that co-occur more often than would be expected by chance. In phraseology, collocation is a sub-type of phraseme. An example of a phraseological collocation, as propounded by Michael Halliday, is the expression strong tea.
Colloquial means the way ordinary people talk informally. It's broader than just slang, although colloquialisms can include slang. A colloquialism is an informal way of saying something that is usually expressed in a more formal way.