Occurrence
The natural form of selenium dioxide, downeyite, is a very rare mineral. It is found in only a very few burning coal dumps.
Read more about this topic: Selenium Dioxide
Famous quotes containing the word occurrence:
“One is absolutely sickened, not by the crimes that the wicked have committed, but by the punishments that the good have inflicted; and a community is infinitely more brutalised by the habitual employment of punishment than it is by the occasional occurrence of crime.”
—Oscar Wilde (1854–1900)