Yeah the Russians knew, it's just no one knew exactly how much of the minerals were in these deposits until the US geologist did some advanced surveys in 04, the articles says they flew an "old Navy Orion P-3 over 70% of the country using advanced gravity and magnetic measuring equipment attached to it", then in 07 they came back with even more advanced equipment using an "old British bomber equipped with instruments that offered a three-dimensional profile of mineral deposits below the earth’s surface", the article also said "It was the most comprehensive geologic survey of Afghanistan ever conducted", so it sounds like the Russians didn't know the extent of the deposits, only that they existed.