I've never read the very popular and widely beloved Heinlein, but at least I know that good fiction is never just fiction. It delivers truth, as opposed to fact. Indeed, truth can be much clearer in fiction than in fact.
Sorry to pop your bubble, but there isn’t anything on the moon that is worth the cost of getting there and sending it back. What is the most expensive raw material on earth? Platinum? Gold? Both somewhere around $1700/ounce. IN 1976 dollars the cost of an ounce of moon rocks was about $1,783,000 due to the transportation costs. Let me know what raw material that you think is on the moon that is worth that much