Black shales
Au-Pd-Ag mineralization in black shales of Onega depression, Karelia, Russia
N.S. Rudashevsky, Yo.L. Kretser
Grains of precious metal minerals from black shales of Onega depression (1-9); SEM images (BIE)
1-4 — numbers of analysis of one grain; POR — pores; Pd — native palladium; Au, Au3Ag, (Au,Ag,Pd), (Au,Cu,Ag), (Au,Ag,Pd,Cu)— native gold, Bi2O3 — bismite. 5 — part of 4; 7 — part of 6; 9 — part of 8.
Chemical composition (wt. %) of noble metal minerals from black shales of Onega depression
| Anal. | Au | Ag | Pd | Cu | Fe | Total | Photo and point of analysis | Phases |
|---|---|---|---|---|---|---|---|---|
| 1 | 85.8 | 14.0 | - | - | - | 99.8 | 1 | Au3Ag |
| 2 | 60.5 | 27.2 | - | 12.1 | - | 99.8 | - | (Au,Ag,Pd)3Cu |
| 3 | 86.1 | 7.5 | - | 6.4 | - | 100.0 | 2 | (Au,Ag,Pd)3Cu |
| 4 | 62.2 | 8.1 | 1.5 | 27.1 | 0.6 | 100.0 | - | (Au,Ag)Cu |
| 5 | 42.2 | 23.2 | - | 34.2 | - | 99.6 | - | (Au,Ag)Cu |
| 6 | 33.3 | 49.7 | 0.5 | 16.0 | - | 99.5 | - | (Au,Ag,Pd)3Cu |
| 7 | 63.4 | 21.1 | 9.4 | 3.7 | 1.6 | 99.2 | 4 & 5, 1 | (Au,Ag,Pd,Cu) |
| 8 | 52.7 | 11.2 | 14.6 | 18.9 | 1.6 | 99.0 | 4 & 5, 3 | (Au,Ag,Pd)3Cu |
| 9 | 66.6 | 14.6 | 11.6 | 5.7 | 1.4 | 99.9 | 4 & 5, 4 | (Au,Ag,Pd,Cu) |
| 10 | 9.2 | 1.6 | 83.3 | 5.4 | 0.8 | 100.0 | 4 & 5, 2 | (Pd,Cu,Ag) |
| 11 | 67.9 | 20.6 | 10.1 | 1.3 | - | 99.9 | 6 & 7 | (Au,Ag,Pd) |
| 12 | 59.9 | 24.7 | 14.8 | 0.6 | - | 100.0 | 3, 1 | (Au,Ag,Pd) |
| 13 | 69.8 | 12.8 | 16.6 | 0.8 | - | 100.0 | 3, 2 | (Au,Pd,Ag) |
| 14 | 94.3 | 3.8 | 0.5 | 1.5 | - | 100.1 | - | Au |
| 15 | 92.6 | 6.9 | - | - | - | 99.5 | 8 | (Au,Ag) |
| 16 | 92.7 | 6.9 | - | - | - | 99.6 | 8 | (Au,Ag) |
| 17 | 98.2 | 1.8 | - | - | - | 100.0 | 9 | Au |
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