Gold element silver (as electrum) and also naturally alloyed with copper and palladium. Less commonly, it occurs in minerals as gold compounds, often with tellurium (gold tellurides). Gold is resistant to most acids, though it does dissolve in aqua regia, a mixture of nitric acid and hydrochloric acid, which forms a soluble tetrachloroaurate anion. Gold is insoluble in nitric acid, which dissolves silver and base metals, a property that has long been used to refine gold and to confirm the presence of gold in metallic objects, giving rise to the term "acid test". Gold also dissolves in alkaline solutions of cyanide,
Metal Gear Acid a trading card-based system to control the main character's movements and actions. "Acid" in the name stands for "Active Command Intelligence Duel". The cards are not truly collectible, as the game is complete with a single purchase. However, the game does feature deck design and deck optimization elements. The game allows for multiplayer gameplay by wireless ad-hoc connections of two PSPs. Before each round, the player can customize the deck of cards used by the main characters. The majority of the cards are based upon elements spanning the entire "Metal Gear" series, such as weaponry, characters, and even the Metal