Sulfur hexafluoride is an dense, incredibly potent, long lived greenhouse gas, with a greenhouse potency of over 23,900 times that of CO2, an atmospheric lifetime of 800–3,200 years, and a density almost 6x that of Air. It is useful in greenhouses and other structures as a buffer gas, and to help maintain habitable temperatures. It has also been suggested as a means to terraform areas on mars, although using it at small scale to microterraform craters is more feasible.
SF6 can be created readily using S and NaF, which are common byproducts of mining.
- S + (2 + x) Br2 + 4 KF → SF4↑ + x Br2 + 4 KBr (~20-80C) 
- 2 CoF3 + SF4 + [Br2] → SF6 + 2 CoF2 + [Br2] (~100C) 
With a theorized step to regenerate the CoF3 from HF or F2 as needed, forming a loop.