TL;DR: 16 Psyche is the largest metallic asteroid and the primary target for asteroid mining concepts. It may be the exposed core of a protoplanet that lost its mantle through collisions. The NASA Psyche mis
16 Psyche is the largest metallic asteroid and the primary target for asteroid mining concepts. It may be the exposed core of a protoplanet that lost its mantle through collisions. The NASA Psyche mission will map its composition in detail starting 2029.
Composition
Iron-nickel core (kamacite, taenite); possible gold, platinum, cobalt
Orbit
2.9 AU (main belt), period 4.99 years
Mining Potential
Highest - estimated $10 quintillion metal value; NASA Psyche mission en route (arrival 2029)
Mission
NASA Psyche (launched Oct 2023, arrival Aug 2029)