need help with this question

Question

what kinds of environmentals cause a crystal to form

Answer 1

i need to know if this is correct would the answer be

calcite and dolomite

Answer 2

I don't think so. Calcite and dolomite are crystals but that isn't an environmental answer. See these sites.
http://www.rensselaer.org/dept/chem-eng/Biotech-Environ/DOWNSTREAM/form.htm

http://en.wikipedia.org/wiki/Mineral