Which is characteristic of a mineral?
it must be naturally occuring and crystalline
it must be man-made and crystalline
it must be man-made and amorphous
it must be naturally occurring and amorphous

Two liquids are poured into a beaker. after a few seconds, the beaker becomes warm. which of the following best describes this reaction? a. an exothermic reaction b. a decomposition reaction c. an endothermic reaction d. a single-displacement reaction