<p>Sentence: The compositions are a consequence of the environment of crystallization.</p>
<p>Is the above sentence correct or should “a consequence” be changed into “consequences”?</p>
<p>Yes, you should change the error to “consequences.”</p>
<p>No, the original sentence is grammatically correct. The “compositions” make up the entire result of the environment of crystallization. There aren’t several results just because the result embodies something plural. If my (hypothetical) wife and I have twins, then the twins are a single RESULT of a single act, not two results. If my wife becomes fat in the process, then her becoming fat and her having twins are two outcomes of the pregnancy.</p>