The Asteroid Eros was closely examined in 1999 by the Near Earth Asteroid Rendezvous spacecraft. Few Asteroids have been closely examined, and it is believed that Eros may not be unusual in the minerals it contains. There are 1000s of asteroids circling earth. Weighing in at about 20,000 million tons of aluminum and with almost the same amount of gold and platinum, one has to wonder why NASA hasn’t launched a mission to capture the banana shaped asteroid, tethered it to the international space station, and started one of the largest mining projects in the history of the world— in space.
In fact, the amount of precious stone in this not particularly large Asteroid is greater than what could be mined from the entire upper crust of our planet. Twenty to 200 thousand megatons of explosives would be needed to extract substantial amounts of precious minerals. Such a project would more realistically be done by mining on the rock itself by a spacecraft using solar energy and robots.