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Natural
Gamma Ray
emission from subsurface rocks
Table 1.
Typical
GR
values for popular minerals
Rock Type
GR
,
GAPI
1
Halite (Rock Salt)
0
2
Coal
0
3
Limestone
5 – 10
4
Sandstone
10 – 20
5
Dolomite
10 – 20
6
Shale
80 – 140
7
Mica
100 – 170
8
Sylvite (KCl)
500