How much spice was in the Atreides lost harvester?

Duke Leto Atreides commanded fierce loyalty from his subjects, a large part of which comes from his reciprocal loyalty to them, and this is neatly portrayed in the book:

• Leto, Paul, Liet-Kynes and co. fly an ornithopter to a spice harvester in the field


• It is attacked by a worm


• Rather than accept the loss or attempt to salvage spice, Leto (unexpectedly) ordered an impromptu rescue operation, saving the entire harvester crew, but losing a full load of unrefined spice

This action went a large way towards winning the allegiance of the xenophobic Fremen.

It is heavily implied that this was a highly unusual noble act, due to the high amount and cost of spice lost. How much value was lost, exactly? We know that "one briefcase full of spice would be enough to purchase an entire planet", but in this case:

• The spice was unrefined


• The amount was a full harvester load

How much, approximately, would this estimate to be?