rockwool is "trash" it will NOT break down.we have piles that have sat in our compost and if u dig in the compost the cubes at the bottom havent even started to breakdown.some are 5-6 years old.even if u crush it up it doesnt seam to help.its been a problem for us for awhile,"what to do with it"theres plenty of forest where we live and the prop. has had a number of old grow spots from past owners.we have had to spend days cleaning up piles of rockwool,nute bottles,plastic piping,and wire.the rockwool from these old grows are still useable if u had nothing else.
dont mean to give u a hard time about it but our collective has spent countless days cleaning up old grows in norcal and we are hoping that u will go back and clean up the trash u have dumped.