 Why is Acoustix so valuable?
"However, as you perhaps know, the only reason for colonial activities here at all is because of the presence of an ore known as Acoustix. It's no use to the people of Earth but of untold value on Mars. Then it was found that this ore, Acoustix, revitalized their sounding apparatus, and the rush was on." So now here we were at the outer reaches of the Baldric, four travelers on foot with only the barest necessities in the way of equipment and supplies. Struck a rich vein of Acoustix that runs deep in. In another chamber the extremely light Acoustix ore was being packed into big cases and marked for shipment.
 It helps Martain people regain their ability to communicate.
 Acoustix can be sold at a high price.  It's an ore that can only be found in one place.  It helps Martain people regain their ability to communicate.  It's an abundant ore that Earth people sell.