Is there any trace of iron in fiberglass roof shingles?

Question:even if it's the smallest amount, only answer if you know for sure please.

Answers:
Fiberglass shingles are actually made of tar paper reinforced with fiberglass matting, and then covered with silicone sand that has been dyed.
Some of the sand may contain iron impurities. Most roofs are put up with iron fasteners, either nails or staples, .

Got some streaking or discoloration going on?

Good luck.