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.
Collocations: a [text, document, book] excerpt, [highlight, mark] an excerpt from the [text], an excerpt of the [text], more... Forum discussions with the word(s) excerpt in the title: excerpt / extract