Hello,

there is no simple answer to your question. There are many ways to change the composition of a spinel during cooling, interaction with a different melt, hydrous alteration, etc.

What lithology are you studying? What information do you have already?

Eric

Usually this don't too difficult. Primary, growth zoning looks quite different from secondary reactional zoning during metamorphism and metasomatic alterations. The later yoiu can to see here http://www.mindat.org/photo-514893.html enlarged fragment - http://www.mindat.org/photo-514897.html

Unfortunately I haven't under hands photos of primary zonation in chromite.