It's very difficult to dissolve gold. Gold doesn't break down or oxide if left out in the weather like most metals. Aqua regia (King's water), a mixture of two strong acids, will do it. Although that leaves you with chloroauric acid - destructive to human tissue. The first mention of it is in the works of Islamic alchemists such as Muhammad ibn Zakariya al-Razi (854-925) but is there any evidence it was used back then on those mountaintop temples?