I've been holding onto this Rock for more than 20 years, without a clue that it contained Microscopic Gold and lots of it... The Green Solution passed right through the Coffee Filter... This tells me, the Gold was Microscopic and too small to see in the Blue Solution from the Copper... I never would have known, if I didn't soak the Rock in Distilled White Vinegar... The shocking part was when all the invisible Gold started to cling together and become visible...