The zinc oxide minerals in the surficial zone also are sometimes colored yellow by small amounts of greenockite.
"The Economic Aspect of Geology"
C. K. Leith
The remark is made by Brewster that had Newton known the refractive powers of the minerals greenockite and octohedrite, he would have extended the inference to them, and would have been mistaken.
"Logic, Inductive and Deductive"
William Minto
