Table 2.
The acid-soluble and acid insoluble fluoride levels in different rocks.
| Stratum | Lithology | Percentage of acid insoluble substance (%) | Percentage of acid soluble substance (%) | Fluoride level in acid soluble substance (mg/kg) | Percentage of acid soluble fluoride (%) | Fluoride level in acid insoluble substance (mg/kg) |
|---|---|---|---|---|---|---|
| Baota formation of the Mid-Ordovician (O2b) | Silty limestone | 1.93 | 98.07 | 4.71 | 6.72 | 832.34 |
| Wufeng formation of the Late-Ordovician (O3w) | Argillaceous limestone | 2.26 | 97.74 | 9.3 | 7.07 | 1243.64 |
| Maokou formation of the Early-Permian (P1m) | Bioclastic limestone | 1.73 | 98.27 | 14.62 | 19.69 | 995.01 |
| Emeishan formation of the Mid-Permian (P2β) | Basalt | 78.56 | 21.44 | 8.75 | 0.91 | 517.13 |
| Longtan formation of the Mid-Permian (P2l) | Shale | 94.3 | 5.7 | 2.35 | 0.36 | 468.07 |
| Changxing formation of the Mid-Permian (P2c) | Limestone interbedded with shale | 4.84 | 95.16 | 0.8 | 0.66 | 1040.58 |
| Feixianguan formation of the Early-Trias (T1f) | Siltstone | 94.66 | 5.34 | 5.54 | 0.74 | 459.73 |
| Guanling formation of the Mid-Trias (T2g) | Dolomite | 4.61 | 95.39 | 8.85 | 19.22 | 874.48 |
| Xujiahe formation of the Late-Trias (T3x) | Siltstone and sandstone | 91.62 | 8.38 | 28.72 | 12.85 | 402.02 |