Well, here is a study.. Shows that tests were done.

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0127665

Crazy that they don't even mention Geo Engineering though. We have patents on the use of Aluminium for Geo Engineering, man-made nano-sized Aluminium found in the environment and people where spraying occurs.

http://www.geoengineeringwatch.org/tag/aluminum/