11-12-2019, 05:09 PM
Kaliana - most of the MK telescopes do not use mercury. CFHT and Keck have in the past (I don't know if they still do). The mercury was not used to coat the mirrors, it was used as a thin layer to support the outside edges of large mirrors. As randomq mentioned, there have been a few historical spills but all were contained inside the buildings and cleaned up. There are more concerning environmental issues that are a much bigger deal than any mercury that has been used on the summit.