Basalt fibres made from rock solidified from volcanic lava are suggested by some as the alternative to glass fibres. Until recently, they were used solely in the form of basalt ‘wool’ for thermal insulation purposes; however, new technology open for making them into thin wire fibres. The advantage of basalt fibres is the ability to be used with the extreme temperature range of – 200 to + 800C.
One suggested application is as sewing threads for fabrics exposed to high temperatures or adverse chemical environments. Thus, the ecological expense of producing these fibres, stemming mainly from the high temperatures needed.