Impact by Douglas Preston

In Douglas Preston's Impact, Wyman Ford is tapped for a secret expedition to Cambodia... to locate the source of strangely beautiful gemstones that do not appear to be of this world.A brilliant meteor lights up the Maine coast... and two young women borrow a boat and set out for a distant island to find the impact crater.A scientist at the National Propulsion Facility discovers an inexplicable source of gamma rays in the outer Solar System. He is found decapitated, the data missing.High resolution NASA images reveal an unnatural feature hidden in the depths of a crater on Mars... and it appears to have been activated.Sixty hours and counting.