Here's the Cinefoil manufacturer's website, with the link to their own MSDS. It's some sort of epoxy coated aluminum.

I personally wouldn't use this stuff for food, ever. From Section 3 of the MSDS: "If product is heated, inhalation of fumes released from product may cause ‘polymer fume fever’, a flu-like illness." I doubt it would enhance the tea either.

http://us.rosco.com/en/product/cinefoil#product-support-cta