材料                            Uranium    Thorium   Potassium

Granite                         1.7             0.22           32

Sandstone                    0.2              0.19            11

Cement                        1.2             0.57           6.4

Limestone Concrete     0.8               0.23            2.4

Sandstone Concrete     0.3                0.23           10

Drywall                        0.4                0.32          2.4

Natural Gypsum          0.4                 0.2           4

Wood                            -                     -               90

Clay Brick                      3                    1.2             18

Ci是Curie的缩写, 是放射强度的单位，相当于一克Radium的放射性。Curie是发现Radium的居里夫人的姓。