What is the avarage density of gl in HU (Hounsfield Unity)?

The Hounsfield scale is a quantitative scale for describing radiodensity in radiography. Some common values are: -1000 (air), -120 (fat), 0 (water), +30 to +45 (blood), +40 (muscle) and so on. I want to know this value for an avarage piece of gl. Thanks