Gold mining on the Moon

Assume that NASA discovered a gold deposit on the surface of the Moon with average gold grade of 5% by volume. The dimensions of the orebody are 1000m by 1000m by 500m (deep).
Suggest a reliable, efficient and cost effective solution for mining out the gold deposit and for processing the gold.
Make reasonable assumptions for the calculation and about the operating conditions, energy sources, economics for mining and gold processing on the Moon. Assumptions must be justified based on available information and knowledge.