For example.... "Rockwool is a stone-based insulation. It is sourced from abundant lava deposits of volcanic rocks which are melted in a cupola furnace like a controlled man-made volcano. As the re-melted lava comes out of the furnace, it is spun, given water repellency treatment and bound together in a wool-like fleece. Rockwool is a stone wool, which is inorganic and ideal for thermal insulation, fire protection, acoustic control and environmental purposes. "
Also:- B&Q do a range of insulation that comes in a perforated plastic bag...you can lay the insulation direct in the bag, so not needing to get fibres everywhere. the perforations allow moisture in and out.