https://www.theguardian.com/world/2016/nov/30/mexico-temple-wind-god-archaeology-supermarket
Thanks, Duncan: amazing what turns up under supermarkets, car parks etc.
The next news item along deals with a find of liquid mercury (https://www.theguardian.com/world/2015/apr/24/liquid-mercury-mexican-pyramid-teotihuacan) below the Temple of the Feathered Serpent, Teotihuacan, suggesting that archaeologists may be on the track of their first Teotihuacan royal tomb.
Yes, the mercury find is intriguing. The article's from April 2015, and I haven't heard anything newer, unfortunately.