The BBC has just posted an article on recent research on Roman concrete and why it works so well underwater: http://www.bbc.com/news/science-environment-40494248 Coins are not mentioned, but here one from Caesarea Maritima in Israel where a harbor was built using this concrete which sets underwater. Severus Alexander, 222-235 22 mm. 10.36 grams Eagle, wings spread, supporting wreath containing SPQR Sear Greek Imperial 3374, Rosenberger II 86-93.
It's an interesting article and I've read similar things about Roman concrete elsewhere. @4to2centBC beat you to the punch on this particular article but he buried the link in another thread. Edited: Hmm, two different articles but essentially the same content and same time of release.
LOVED the article. Read a lot about Roman Concrete. Additionally, in my view, one of the fundamental aspects of their success is their greatest invention: an easy to make, moldable, durable material used for building. This BUILT an empire. I have a piece of that incredible material... Rome ISCA Legio II Augusta 75-300 CE Caerleon Concrete 2 pcs 26x21mm ea I have no clue where I "picked this up"...
